633 lines
18 KiB
C
633 lines
18 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Copyright (C) 2015 Masahiro Yamada <yamada.masahiro@socionext.com>
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*/
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#include <linux/clk.h>
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#include <linux/i2c.h>
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#include <linux/iopoll.h>
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#include <linux/interrupt.h>
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#include <linux/io.h>
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#include <linux/module.h>
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#include <linux/platform_device.h>
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#define UNIPHIER_FI2C_CR 0x00 /* control register */
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#define UNIPHIER_FI2C_CR_MST BIT(3) /* master mode */
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#define UNIPHIER_FI2C_CR_STA BIT(2) /* start condition */
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#define UNIPHIER_FI2C_CR_STO BIT(1) /* stop condition */
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#define UNIPHIER_FI2C_CR_NACK BIT(0) /* do not return ACK */
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#define UNIPHIER_FI2C_DTTX 0x04 /* TX FIFO */
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#define UNIPHIER_FI2C_DTTX_CMD BIT(8) /* send command (slave addr) */
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#define UNIPHIER_FI2C_DTTX_RD BIT(0) /* read transaction */
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#define UNIPHIER_FI2C_DTRX 0x04 /* RX FIFO */
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#define UNIPHIER_FI2C_SLAD 0x0c /* slave address */
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#define UNIPHIER_FI2C_CYC 0x10 /* clock cycle control */
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#define UNIPHIER_FI2C_LCTL 0x14 /* clock low period control */
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#define UNIPHIER_FI2C_SSUT 0x18 /* restart/stop setup time control */
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#define UNIPHIER_FI2C_DSUT 0x1c /* data setup time control */
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#define UNIPHIER_FI2C_INT 0x20 /* interrupt status */
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#define UNIPHIER_FI2C_IE 0x24 /* interrupt enable */
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#define UNIPHIER_FI2C_IC 0x28 /* interrupt clear */
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#define UNIPHIER_FI2C_INT_TE BIT(9) /* TX FIFO empty */
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#define UNIPHIER_FI2C_INT_RF BIT(8) /* RX FIFO full */
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#define UNIPHIER_FI2C_INT_TC BIT(7) /* send complete (STOP) */
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#define UNIPHIER_FI2C_INT_RC BIT(6) /* receive complete (STOP) */
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#define UNIPHIER_FI2C_INT_TB BIT(5) /* sent specified bytes */
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#define UNIPHIER_FI2C_INT_RB BIT(4) /* received specified bytes */
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#define UNIPHIER_FI2C_INT_NA BIT(2) /* no ACK */
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#define UNIPHIER_FI2C_INT_AL BIT(1) /* arbitration lost */
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#define UNIPHIER_FI2C_SR 0x2c /* status register */
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#define UNIPHIER_FI2C_SR_DB BIT(12) /* device busy */
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#define UNIPHIER_FI2C_SR_STS BIT(11) /* stop condition detected */
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#define UNIPHIER_FI2C_SR_BB BIT(8) /* bus busy */
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#define UNIPHIER_FI2C_SR_RFF BIT(3) /* RX FIFO full */
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#define UNIPHIER_FI2C_SR_RNE BIT(2) /* RX FIFO not empty */
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#define UNIPHIER_FI2C_SR_TNF BIT(1) /* TX FIFO not full */
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#define UNIPHIER_FI2C_SR_TFE BIT(0) /* TX FIFO empty */
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#define UNIPHIER_FI2C_RST 0x34 /* reset control */
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#define UNIPHIER_FI2C_RST_TBRST BIT(2) /* clear TX FIFO */
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#define UNIPHIER_FI2C_RST_RBRST BIT(1) /* clear RX FIFO */
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#define UNIPHIER_FI2C_RST_RST BIT(0) /* forcible bus reset */
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#define UNIPHIER_FI2C_BM 0x38 /* bus monitor */
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#define UNIPHIER_FI2C_BM_SDAO BIT(3) /* output for SDA line */
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#define UNIPHIER_FI2C_BM_SDAS BIT(2) /* readback of SDA line */
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#define UNIPHIER_FI2C_BM_SCLO BIT(1) /* output for SCL line */
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#define UNIPHIER_FI2C_BM_SCLS BIT(0) /* readback of SCL line */
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#define UNIPHIER_FI2C_NOISE 0x3c /* noise filter control */
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#define UNIPHIER_FI2C_TBC 0x40 /* TX byte count setting */
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#define UNIPHIER_FI2C_RBC 0x44 /* RX byte count setting */
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#define UNIPHIER_FI2C_TBCM 0x48 /* TX byte count monitor */
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#define UNIPHIER_FI2C_RBCM 0x4c /* RX byte count monitor */
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#define UNIPHIER_FI2C_BRST 0x50 /* bus reset */
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#define UNIPHIER_FI2C_BRST_FOEN BIT(1) /* normal operation */
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#define UNIPHIER_FI2C_BRST_RSCL BIT(0) /* release SCL */
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#define UNIPHIER_FI2C_INT_FAULTS \
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(UNIPHIER_FI2C_INT_NA | UNIPHIER_FI2C_INT_AL)
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#define UNIPHIER_FI2C_INT_STOP \
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(UNIPHIER_FI2C_INT_TC | UNIPHIER_FI2C_INT_RC)
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#define UNIPHIER_FI2C_RD BIT(0)
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#define UNIPHIER_FI2C_STOP BIT(1)
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#define UNIPHIER_FI2C_MANUAL_NACK BIT(2)
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#define UNIPHIER_FI2C_BYTE_WISE BIT(3)
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#define UNIPHIER_FI2C_DEFER_STOP_COMP BIT(4)
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#define UNIPHIER_FI2C_FIFO_SIZE 8
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struct uniphier_fi2c_priv {
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struct completion comp;
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struct i2c_adapter adap;
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void __iomem *membase;
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struct clk *clk;
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unsigned int len;
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u8 *buf;
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u32 enabled_irqs;
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int error;
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unsigned int flags;
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unsigned int busy_cnt;
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unsigned int clk_cycle;
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spinlock_t lock; /* IRQ synchronization */
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};
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static void uniphier_fi2c_fill_txfifo(struct uniphier_fi2c_priv *priv,
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bool first)
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{
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int fifo_space = UNIPHIER_FI2C_FIFO_SIZE;
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/*
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* TX-FIFO stores slave address in it for the first access.
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* Decrement the counter.
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*/
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if (first)
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fifo_space--;
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while (priv->len) {
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if (fifo_space-- <= 0)
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break;
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writel(*priv->buf++, priv->membase + UNIPHIER_FI2C_DTTX);
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priv->len--;
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}
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}
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static void uniphier_fi2c_drain_rxfifo(struct uniphier_fi2c_priv *priv)
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{
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int fifo_left = priv->flags & UNIPHIER_FI2C_BYTE_WISE ?
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1 : UNIPHIER_FI2C_FIFO_SIZE;
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while (priv->len) {
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if (fifo_left-- <= 0)
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break;
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*priv->buf++ = readl(priv->membase + UNIPHIER_FI2C_DTRX);
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priv->len--;
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}
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}
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static void uniphier_fi2c_set_irqs(struct uniphier_fi2c_priv *priv)
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{
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writel(priv->enabled_irqs, priv->membase + UNIPHIER_FI2C_IE);
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}
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static void uniphier_fi2c_clear_irqs(struct uniphier_fi2c_priv *priv,
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u32 mask)
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{
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writel(mask, priv->membase + UNIPHIER_FI2C_IC);
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}
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static void uniphier_fi2c_stop(struct uniphier_fi2c_priv *priv)
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{
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priv->enabled_irqs |= UNIPHIER_FI2C_INT_STOP;
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uniphier_fi2c_set_irqs(priv);
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writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STO,
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priv->membase + UNIPHIER_FI2C_CR);
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}
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static irqreturn_t uniphier_fi2c_interrupt(int irq, void *dev_id)
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{
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struct uniphier_fi2c_priv *priv = dev_id;
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u32 irq_status;
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spin_lock(&priv->lock);
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irq_status = readl(priv->membase + UNIPHIER_FI2C_INT);
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irq_status &= priv->enabled_irqs;
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if (irq_status & UNIPHIER_FI2C_INT_STOP)
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goto complete;
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if (unlikely(irq_status & UNIPHIER_FI2C_INT_AL)) {
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priv->error = -EAGAIN;
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goto complete;
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}
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if (unlikely(irq_status & UNIPHIER_FI2C_INT_NA)) {
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priv->error = -ENXIO;
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if (priv->flags & UNIPHIER_FI2C_RD) {
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/*
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* work around a hardware bug:
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* The receive-completed interrupt is never set even if
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* STOP condition is detected after the address phase
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* of read transaction fails to get ACK.
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* To avoid time-out error, we issue STOP here,
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* but do not wait for its completion.
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* It should be checked after exiting this handler.
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*/
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uniphier_fi2c_stop(priv);
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priv->flags |= UNIPHIER_FI2C_DEFER_STOP_COMP;
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goto complete;
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}
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goto stop;
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}
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if (irq_status & UNIPHIER_FI2C_INT_TE) {
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if (!priv->len)
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goto data_done;
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uniphier_fi2c_fill_txfifo(priv, false);
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goto handled;
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}
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if (irq_status & (UNIPHIER_FI2C_INT_RF | UNIPHIER_FI2C_INT_RB)) {
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uniphier_fi2c_drain_rxfifo(priv);
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/*
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* If the number of bytes to read is multiple of the FIFO size
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* (msg->len == 8, 16, 24, ...), the INT_RF bit is set a little
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* earlier than INT_RB. We wait for INT_RB to confirm the
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* completion of the current message.
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*/
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if (!priv->len && (irq_status & UNIPHIER_FI2C_INT_RB))
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goto data_done;
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if (unlikely(priv->flags & UNIPHIER_FI2C_MANUAL_NACK)) {
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if (priv->len <= UNIPHIER_FI2C_FIFO_SIZE &&
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!(priv->flags & UNIPHIER_FI2C_BYTE_WISE)) {
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priv->enabled_irqs |= UNIPHIER_FI2C_INT_RB;
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uniphier_fi2c_set_irqs(priv);
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priv->flags |= UNIPHIER_FI2C_BYTE_WISE;
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}
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if (priv->len <= 1)
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writel(UNIPHIER_FI2C_CR_MST |
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UNIPHIER_FI2C_CR_NACK,
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priv->membase + UNIPHIER_FI2C_CR);
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}
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goto handled;
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}
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spin_unlock(&priv->lock);
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return IRQ_NONE;
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data_done:
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if (priv->flags & UNIPHIER_FI2C_STOP) {
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stop:
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uniphier_fi2c_stop(priv);
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} else {
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complete:
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priv->enabled_irqs = 0;
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uniphier_fi2c_set_irqs(priv);
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complete(&priv->comp);
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}
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handled:
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/*
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* This controller makes a pause while any bit of the IRQ status is
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* asserted. Clear the asserted bit to kick the controller just before
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* exiting the handler.
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*/
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uniphier_fi2c_clear_irqs(priv, irq_status);
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spin_unlock(&priv->lock);
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return IRQ_HANDLED;
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}
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static void uniphier_fi2c_tx_init(struct uniphier_fi2c_priv *priv, u16 addr,
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bool repeat)
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{
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priv->enabled_irqs |= UNIPHIER_FI2C_INT_TE;
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uniphier_fi2c_set_irqs(priv);
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/* do not use TX byte counter */
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writel(0, priv->membase + UNIPHIER_FI2C_TBC);
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/* set slave address */
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writel(UNIPHIER_FI2C_DTTX_CMD | addr << 1,
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priv->membase + UNIPHIER_FI2C_DTTX);
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/*
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* First chunk of data. For a repeated START condition, do not write
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* data to the TX fifo here to avoid the timing issue.
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*/
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if (!repeat)
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uniphier_fi2c_fill_txfifo(priv, true);
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}
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static void uniphier_fi2c_rx_init(struct uniphier_fi2c_priv *priv, u16 addr)
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{
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priv->flags |= UNIPHIER_FI2C_RD;
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if (likely(priv->len < 256)) {
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/*
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* If possible, use RX byte counter.
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* It can automatically handle NACK for the last byte.
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*/
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writel(priv->len, priv->membase + UNIPHIER_FI2C_RBC);
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priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF |
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UNIPHIER_FI2C_INT_RB;
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} else {
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/*
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* The byte counter can not count over 256. In this case,
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* do not use it at all. Drain data when FIFO gets full,
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* but treat the last portion as a special case.
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*/
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writel(0, priv->membase + UNIPHIER_FI2C_RBC);
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priv->flags |= UNIPHIER_FI2C_MANUAL_NACK;
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priv->enabled_irqs |= UNIPHIER_FI2C_INT_RF;
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}
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uniphier_fi2c_set_irqs(priv);
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/* set slave address with RD bit */
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writel(UNIPHIER_FI2C_DTTX_CMD | UNIPHIER_FI2C_DTTX_RD | addr << 1,
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priv->membase + UNIPHIER_FI2C_DTTX);
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}
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static void uniphier_fi2c_reset(struct uniphier_fi2c_priv *priv)
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{
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writel(UNIPHIER_FI2C_RST_RST, priv->membase + UNIPHIER_FI2C_RST);
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}
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static void uniphier_fi2c_prepare_operation(struct uniphier_fi2c_priv *priv)
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{
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writel(UNIPHIER_FI2C_BRST_FOEN | UNIPHIER_FI2C_BRST_RSCL,
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priv->membase + UNIPHIER_FI2C_BRST);
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}
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static void uniphier_fi2c_recover(struct uniphier_fi2c_priv *priv)
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{
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uniphier_fi2c_reset(priv);
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i2c_recover_bus(&priv->adap);
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}
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static int uniphier_fi2c_master_xfer_one(struct i2c_adapter *adap,
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struct i2c_msg *msg, bool repeat,
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bool stop)
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{
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struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
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bool is_read = msg->flags & I2C_M_RD;
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unsigned long time_left, flags;
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priv->len = msg->len;
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priv->buf = msg->buf;
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priv->enabled_irqs = UNIPHIER_FI2C_INT_FAULTS;
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priv->error = 0;
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priv->flags = 0;
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if (stop)
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priv->flags |= UNIPHIER_FI2C_STOP;
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reinit_completion(&priv->comp);
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uniphier_fi2c_clear_irqs(priv, U32_MAX);
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writel(UNIPHIER_FI2C_RST_TBRST | UNIPHIER_FI2C_RST_RBRST,
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priv->membase + UNIPHIER_FI2C_RST); /* reset TX/RX FIFO */
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spin_lock_irqsave(&priv->lock, flags);
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if (is_read)
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uniphier_fi2c_rx_init(priv, msg->addr);
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else
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uniphier_fi2c_tx_init(priv, msg->addr, repeat);
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/*
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* For a repeated START condition, writing a slave address to the FIFO
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* kicks the controller. So, the UNIPHIER_FI2C_CR register should be
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* written only for a non-repeated START condition.
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*/
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if (!repeat)
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writel(UNIPHIER_FI2C_CR_MST | UNIPHIER_FI2C_CR_STA,
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priv->membase + UNIPHIER_FI2C_CR);
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spin_unlock_irqrestore(&priv->lock, flags);
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time_left = wait_for_completion_timeout(&priv->comp, adap->timeout);
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spin_lock_irqsave(&priv->lock, flags);
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priv->enabled_irqs = 0;
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uniphier_fi2c_set_irqs(priv);
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spin_unlock_irqrestore(&priv->lock, flags);
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if (!time_left) {
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dev_err(&adap->dev, "transaction timeout.\n");
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uniphier_fi2c_recover(priv);
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return -ETIMEDOUT;
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}
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if (unlikely(priv->flags & UNIPHIER_FI2C_DEFER_STOP_COMP)) {
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u32 status;
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int ret;
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ret = readl_poll_timeout(priv->membase + UNIPHIER_FI2C_SR,
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status,
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(status & UNIPHIER_FI2C_SR_STS) &&
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!(status & UNIPHIER_FI2C_SR_BB),
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1, 20);
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if (ret) {
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dev_err(&adap->dev,
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"stop condition was not completed.\n");
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uniphier_fi2c_recover(priv);
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return ret;
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}
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}
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return priv->error;
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}
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static int uniphier_fi2c_check_bus_busy(struct i2c_adapter *adap)
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{
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struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
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if (readl(priv->membase + UNIPHIER_FI2C_SR) & UNIPHIER_FI2C_SR_DB) {
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if (priv->busy_cnt++ > 3) {
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/*
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* If bus busy continues too long, it is probably
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* in a wrong state. Try bus recovery.
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*/
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uniphier_fi2c_recover(priv);
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priv->busy_cnt = 0;
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}
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return -EAGAIN;
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}
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priv->busy_cnt = 0;
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return 0;
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}
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static int uniphier_fi2c_master_xfer(struct i2c_adapter *adap,
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struct i2c_msg *msgs, int num)
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{
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struct i2c_msg *msg, *emsg = msgs + num;
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bool repeat = false;
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int ret;
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ret = uniphier_fi2c_check_bus_busy(adap);
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if (ret)
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return ret;
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for (msg = msgs; msg < emsg; msg++) {
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/* Emit STOP if it is the last message or I2C_M_STOP is set. */
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bool stop = (msg + 1 == emsg) || (msg->flags & I2C_M_STOP);
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ret = uniphier_fi2c_master_xfer_one(adap, msg, repeat, stop);
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if (ret)
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return ret;
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repeat = !stop;
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}
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return num;
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}
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static u32 uniphier_fi2c_functionality(struct i2c_adapter *adap)
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{
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return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
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}
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static const struct i2c_algorithm uniphier_fi2c_algo = {
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.master_xfer = uniphier_fi2c_master_xfer,
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.functionality = uniphier_fi2c_functionality,
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};
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static int uniphier_fi2c_get_scl(struct i2c_adapter *adap)
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{
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struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
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return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
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UNIPHIER_FI2C_BM_SCLS);
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}
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static void uniphier_fi2c_set_scl(struct i2c_adapter *adap, int val)
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{
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struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
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writel(val ? UNIPHIER_FI2C_BRST_RSCL : 0,
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priv->membase + UNIPHIER_FI2C_BRST);
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}
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static int uniphier_fi2c_get_sda(struct i2c_adapter *adap)
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{
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struct uniphier_fi2c_priv *priv = i2c_get_adapdata(adap);
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return !!(readl(priv->membase + UNIPHIER_FI2C_BM) &
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UNIPHIER_FI2C_BM_SDAS);
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}
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static void uniphier_fi2c_unprepare_recovery(struct i2c_adapter *adap)
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{
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uniphier_fi2c_prepare_operation(i2c_get_adapdata(adap));
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}
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static struct i2c_bus_recovery_info uniphier_fi2c_bus_recovery_info = {
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.recover_bus = i2c_generic_scl_recovery,
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.get_scl = uniphier_fi2c_get_scl,
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.set_scl = uniphier_fi2c_set_scl,
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.get_sda = uniphier_fi2c_get_sda,
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.unprepare_recovery = uniphier_fi2c_unprepare_recovery,
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};
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static void uniphier_fi2c_hw_init(struct uniphier_fi2c_priv *priv)
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{
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unsigned int cyc = priv->clk_cycle;
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u32 tmp;
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tmp = readl(priv->membase + UNIPHIER_FI2C_CR);
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tmp |= UNIPHIER_FI2C_CR_MST;
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writel(tmp, priv->membase + UNIPHIER_FI2C_CR);
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uniphier_fi2c_reset(priv);
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/*
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* Standard-mode: tLOW + tHIGH = 10 us
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* Fast-mode: tLOW + tHIGH = 2.5 us
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*/
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writel(cyc, priv->membase + UNIPHIER_FI2C_CYC);
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/*
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* Standard-mode: tLOW = 4.7 us, tHIGH = 4.0 us, tBUF = 4.7 us
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* Fast-mode: tLOW = 1.3 us, tHIGH = 0.6 us, tBUF = 1.3 us
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* "tLow/tHIGH = 5/4" meets both.
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*/
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writel(cyc * 5 / 9, priv->membase + UNIPHIER_FI2C_LCTL);
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/*
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* Standard-mode: tHD;STA = 4.0 us, tSU;STA = 4.7 us, tSU;STO = 4.0 us
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* Fast-mode: tHD;STA = 0.6 us, tSU;STA = 0.6 us, tSU;STO = 0.6 us
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*/
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writel(cyc / 2, priv->membase + UNIPHIER_FI2C_SSUT);
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/*
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* Standard-mode: tSU;DAT = 250 ns
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* Fast-mode: tSU;DAT = 100 ns
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*/
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writel(cyc / 16, priv->membase + UNIPHIER_FI2C_DSUT);
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uniphier_fi2c_prepare_operation(priv);
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}
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static int uniphier_fi2c_probe(struct platform_device *pdev)
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{
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struct device *dev = &pdev->dev;
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struct uniphier_fi2c_priv *priv;
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u32 bus_speed;
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unsigned long clk_rate;
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int irq, ret;
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priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
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if (!priv)
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return -ENOMEM;
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priv->membase = devm_platform_ioremap_resource(pdev, 0);
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if (IS_ERR(priv->membase))
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return PTR_ERR(priv->membase);
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irq = platform_get_irq(pdev, 0);
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if (irq < 0)
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return irq;
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if (of_property_read_u32(dev->of_node, "clock-frequency", &bus_speed))
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bus_speed = I2C_MAX_STANDARD_MODE_FREQ;
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if (!bus_speed || bus_speed > I2C_MAX_FAST_MODE_FREQ) {
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dev_err(dev, "invalid clock-frequency %d\n", bus_speed);
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return -EINVAL;
|
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}
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priv->clk = devm_clk_get_enabled(dev, NULL);
|
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if (IS_ERR(priv->clk)) {
|
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dev_err(dev, "failed to enable clock\n");
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return PTR_ERR(priv->clk);
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}
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clk_rate = clk_get_rate(priv->clk);
|
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if (!clk_rate) {
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dev_err(dev, "input clock rate should not be zero\n");
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return -EINVAL;
|
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}
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|
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priv->clk_cycle = clk_rate / bus_speed;
|
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init_completion(&priv->comp);
|
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spin_lock_init(&priv->lock);
|
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priv->adap.owner = THIS_MODULE;
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priv->adap.algo = &uniphier_fi2c_algo;
|
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priv->adap.dev.parent = dev;
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priv->adap.dev.of_node = dev->of_node;
|
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strscpy(priv->adap.name, "UniPhier FI2C", sizeof(priv->adap.name));
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priv->adap.bus_recovery_info = &uniphier_fi2c_bus_recovery_info;
|
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i2c_set_adapdata(&priv->adap, priv);
|
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platform_set_drvdata(pdev, priv);
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|
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uniphier_fi2c_hw_init(priv);
|
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|
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ret = devm_request_irq(dev, irq, uniphier_fi2c_interrupt, 0,
|
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pdev->name, priv);
|
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if (ret) {
|
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dev_err(dev, "failed to request irq %d\n", irq);
|
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return ret;
|
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}
|
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|
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return i2c_add_adapter(&priv->adap);
|
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}
|
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|
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static void uniphier_fi2c_remove(struct platform_device *pdev)
|
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{
|
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struct uniphier_fi2c_priv *priv = platform_get_drvdata(pdev);
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|
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i2c_del_adapter(&priv->adap);
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}
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static int __maybe_unused uniphier_fi2c_suspend(struct device *dev)
|
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{
|
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struct uniphier_fi2c_priv *priv = dev_get_drvdata(dev);
|
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|
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clk_disable_unprepare(priv->clk);
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|
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return 0;
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}
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|
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static int __maybe_unused uniphier_fi2c_resume(struct device *dev)
|
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{
|
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struct uniphier_fi2c_priv *priv = dev_get_drvdata(dev);
|
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int ret;
|
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|
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ret = clk_prepare_enable(priv->clk);
|
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if (ret)
|
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return ret;
|
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|
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uniphier_fi2c_hw_init(priv);
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|
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return 0;
|
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}
|
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|
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static const struct dev_pm_ops uniphier_fi2c_pm_ops = {
|
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SET_SYSTEM_SLEEP_PM_OPS(uniphier_fi2c_suspend, uniphier_fi2c_resume)
|
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};
|
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|
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static const struct of_device_id uniphier_fi2c_match[] = {
|
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{ .compatible = "socionext,uniphier-fi2c" },
|
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{ /* sentinel */ }
|
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};
|
|
MODULE_DEVICE_TABLE(of, uniphier_fi2c_match);
|
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|
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static struct platform_driver uniphier_fi2c_drv = {
|
|
.probe = uniphier_fi2c_probe,
|
|
.remove_new = uniphier_fi2c_remove,
|
|
.driver = {
|
|
.name = "uniphier-fi2c",
|
|
.of_match_table = uniphier_fi2c_match,
|
|
.pm = &uniphier_fi2c_pm_ops,
|
|
},
|
|
};
|
|
module_platform_driver(uniphier_fi2c_drv);
|
|
|
|
MODULE_AUTHOR("Masahiro Yamada <yamada.masahiro@socionext.com>");
|
|
MODULE_DESCRIPTION("UniPhier FIFO-builtin I2C bus driver");
|
|
MODULE_LICENSE("GPL");
|