538 lines
14 KiB
C
538 lines
14 KiB
C
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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* Bitbanging I2C bus driver using the GPIO API
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*
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* Copyright (C) 2007 Atmel Corporation
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*/
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#include <linux/completion.h>
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#include <linux/debugfs.h>
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#include <linux/delay.h>
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#include <linux/gpio/consumer.h>
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#include <linux/i2c-algo-bit.h>
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#include <linux/i2c.h>
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#include <linux/init.h>
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#include <linux/interrupt.h>
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#include <linux/module.h>
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#include <linux/platform_data/i2c-gpio.h>
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#include <linux/platform_device.h>
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#include <linux/property.h>
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#include <linux/slab.h>
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struct i2c_gpio_private_data {
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struct gpio_desc *sda;
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struct gpio_desc *scl;
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struct i2c_adapter adap;
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struct i2c_algo_bit_data bit_data;
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struct i2c_gpio_platform_data pdata;
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#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
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struct dentry *debug_dir;
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/* these must be protected by bus lock */
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struct completion scl_irq_completion;
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u64 scl_irq_data;
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#endif
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};
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/*
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* Toggle SDA by changing the output value of the pin. This is only
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* valid for pins configured as open drain (i.e. setting the value
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* high effectively turns off the output driver.)
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*/
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static void i2c_gpio_setsda_val(void *data, int state)
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{
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struct i2c_gpio_private_data *priv = data;
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gpiod_set_value_cansleep(priv->sda, state);
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}
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/*
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* Toggle SCL by changing the output value of the pin. This is used
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* for pins that are configured as open drain and for output-only
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* pins. The latter case will break the i2c protocol, but it will
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* often work in practice.
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*/
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static void i2c_gpio_setscl_val(void *data, int state)
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{
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struct i2c_gpio_private_data *priv = data;
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gpiod_set_value_cansleep(priv->scl, state);
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}
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static int i2c_gpio_getsda(void *data)
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{
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struct i2c_gpio_private_data *priv = data;
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return gpiod_get_value_cansleep(priv->sda);
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}
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static int i2c_gpio_getscl(void *data)
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{
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struct i2c_gpio_private_data *priv = data;
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return gpiod_get_value_cansleep(priv->scl);
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}
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#ifdef CONFIG_I2C_GPIO_FAULT_INJECTOR
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static struct dentry *i2c_gpio_debug_dir;
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#define setsda(bd, val) ((bd)->setsda((bd)->data, val))
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#define setscl(bd, val) ((bd)->setscl((bd)->data, val))
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#define getsda(bd) ((bd)->getsda((bd)->data))
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#define getscl(bd) ((bd)->getscl((bd)->data))
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#define WIRE_ATTRIBUTE(wire) \
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static int fops_##wire##_get(void *data, u64 *val) \
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{ \
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struct i2c_gpio_private_data *priv = data; \
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\
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i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
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*val = get##wire(&priv->bit_data); \
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i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
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return 0; \
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} \
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static int fops_##wire##_set(void *data, u64 val) \
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{ \
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struct i2c_gpio_private_data *priv = data; \
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\
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i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
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set##wire(&priv->bit_data, val); \
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i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER); \
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return 0; \
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} \
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DEFINE_DEBUGFS_ATTRIBUTE(fops_##wire, fops_##wire##_get, fops_##wire##_set, "%llu\n")
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WIRE_ATTRIBUTE(scl);
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WIRE_ATTRIBUTE(sda);
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static void i2c_gpio_incomplete_transfer(struct i2c_gpio_private_data *priv,
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u32 pattern, u8 pattern_size)
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{
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struct i2c_algo_bit_data *bit_data = &priv->bit_data;
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int i;
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i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
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/* START condition */
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setsda(bit_data, 0);
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udelay(bit_data->udelay);
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/* Send pattern, request ACK, don't send STOP */
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for (i = pattern_size - 1; i >= 0; i--) {
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setscl(bit_data, 0);
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udelay(bit_data->udelay / 2);
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setsda(bit_data, (pattern >> i) & 1);
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udelay((bit_data->udelay + 1) / 2);
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setscl(bit_data, 1);
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udelay(bit_data->udelay);
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}
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i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
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}
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static int fops_incomplete_addr_phase_set(void *data, u64 addr)
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{
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struct i2c_gpio_private_data *priv = data;
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u32 pattern;
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if (addr > 0x7f)
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return -EINVAL;
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/* ADDR (7 bit) + RD (1 bit) + Client ACK, keep SDA hi (1 bit) */
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pattern = (addr << 2) | 3;
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i2c_gpio_incomplete_transfer(priv, pattern, 9);
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return 0;
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}
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DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_addr_phase, NULL, fops_incomplete_addr_phase_set, "%llu\n");
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static int fops_incomplete_write_byte_set(void *data, u64 addr)
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{
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struct i2c_gpio_private_data *priv = data;
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u32 pattern;
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if (addr > 0x7f)
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return -EINVAL;
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/* ADDR (7 bit) + WR (1 bit) + Client ACK (1 bit) */
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pattern = (addr << 2) | 1;
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/* 0x00 (8 bit) + Client ACK, keep SDA hi (1 bit) */
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pattern = (pattern << 9) | 1;
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i2c_gpio_incomplete_transfer(priv, pattern, 18);
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return 0;
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}
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DEFINE_DEBUGFS_ATTRIBUTE(fops_incomplete_write_byte, NULL, fops_incomplete_write_byte_set, "%llu\n");
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static int i2c_gpio_fi_act_on_scl_irq(struct i2c_gpio_private_data *priv,
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irqreturn_t handler(int, void*))
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{
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int ret, irq = gpiod_to_irq(priv->scl);
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if (irq < 0)
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return irq;
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i2c_lock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
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ret = gpiod_direction_input(priv->scl);
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if (ret)
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goto unlock;
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reinit_completion(&priv->scl_irq_completion);
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ret = request_irq(irq, handler, IRQF_TRIGGER_FALLING,
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"i2c_gpio_fault_injector_scl_irq", priv);
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if (ret)
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goto output;
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wait_for_completion_interruptible(&priv->scl_irq_completion);
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free_irq(irq, priv);
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output:
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ret = gpiod_direction_output(priv->scl, 1) ?: ret;
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unlock:
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i2c_unlock_bus(&priv->adap, I2C_LOCK_ROOT_ADAPTER);
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return ret;
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}
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static irqreturn_t lose_arbitration_irq(int irq, void *dev_id)
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{
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struct i2c_gpio_private_data *priv = dev_id;
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setsda(&priv->bit_data, 0);
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udelay(priv->scl_irq_data);
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setsda(&priv->bit_data, 1);
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complete(&priv->scl_irq_completion);
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return IRQ_HANDLED;
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}
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static int fops_lose_arbitration_set(void *data, u64 duration)
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{
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struct i2c_gpio_private_data *priv = data;
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if (duration > 100 * 1000)
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return -EINVAL;
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priv->scl_irq_data = duration;
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/*
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* Interrupt on falling SCL. This ensures that the master under test has
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* really started the transfer. Interrupt on falling SDA did only
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* exercise 'bus busy' detection on some HW but not 'arbitration lost'.
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* Note that the interrupt latency may cause the first bits to be
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* transmitted correctly.
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*/
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return i2c_gpio_fi_act_on_scl_irq(priv, lose_arbitration_irq);
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}
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DEFINE_DEBUGFS_ATTRIBUTE(fops_lose_arbitration, NULL, fops_lose_arbitration_set, "%llu\n");
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static irqreturn_t inject_panic_irq(int irq, void *dev_id)
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{
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struct i2c_gpio_private_data *priv = dev_id;
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udelay(priv->scl_irq_data);
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panic("I2C fault injector induced panic");
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return IRQ_HANDLED;
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}
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static int fops_inject_panic_set(void *data, u64 duration)
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{
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struct i2c_gpio_private_data *priv = data;
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if (duration > 100 * 1000)
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return -EINVAL;
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priv->scl_irq_data = duration;
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/*
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* Interrupt on falling SCL. This ensures that the master under test has
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* really started the transfer.
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*/
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return i2c_gpio_fi_act_on_scl_irq(priv, inject_panic_irq);
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}
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DEFINE_DEBUGFS_ATTRIBUTE(fops_inject_panic, NULL, fops_inject_panic_set, "%llu\n");
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static void i2c_gpio_fault_injector_init(struct platform_device *pdev)
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{
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struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
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/*
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* If there will be a debugfs-dir per i2c adapter somewhen, put the
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* 'fault-injector' dir there. Until then, we have a global dir with
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* all adapters as subdirs.
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*/
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if (!i2c_gpio_debug_dir) {
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i2c_gpio_debug_dir = debugfs_create_dir("i2c-fault-injector", NULL);
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if (!i2c_gpio_debug_dir)
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return;
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}
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priv->debug_dir = debugfs_create_dir(pdev->name, i2c_gpio_debug_dir);
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if (!priv->debug_dir)
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return;
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init_completion(&priv->scl_irq_completion);
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debugfs_create_file_unsafe("incomplete_address_phase", 0200, priv->debug_dir,
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priv, &fops_incomplete_addr_phase);
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debugfs_create_file_unsafe("incomplete_write_byte", 0200, priv->debug_dir,
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priv, &fops_incomplete_write_byte);
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if (priv->bit_data.getscl) {
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debugfs_create_file_unsafe("inject_panic", 0200, priv->debug_dir,
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priv, &fops_inject_panic);
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debugfs_create_file_unsafe("lose_arbitration", 0200, priv->debug_dir,
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priv, &fops_lose_arbitration);
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}
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debugfs_create_file_unsafe("scl", 0600, priv->debug_dir, priv, &fops_scl);
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debugfs_create_file_unsafe("sda", 0600, priv->debug_dir, priv, &fops_sda);
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}
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static void i2c_gpio_fault_injector_exit(struct platform_device *pdev)
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{
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struct i2c_gpio_private_data *priv = platform_get_drvdata(pdev);
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debugfs_remove_recursive(priv->debug_dir);
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}
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#else
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static inline void i2c_gpio_fault_injector_init(struct platform_device *pdev) {}
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static inline void i2c_gpio_fault_injector_exit(struct platform_device *pdev) {}
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#endif /* CONFIG_I2C_GPIO_FAULT_INJECTOR*/
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/* Get i2c-gpio properties from DT or ACPI table */
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static void i2c_gpio_get_properties(struct device *dev,
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struct i2c_gpio_platform_data *pdata)
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{
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u32 reg;
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device_property_read_u32(dev, "i2c-gpio,delay-us", &pdata->udelay);
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if (!device_property_read_u32(dev, "i2c-gpio,timeout-ms", ®))
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pdata->timeout = msecs_to_jiffies(reg);
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pdata->sda_is_open_drain =
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device_property_read_bool(dev, "i2c-gpio,sda-open-drain");
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pdata->scl_is_open_drain =
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device_property_read_bool(dev, "i2c-gpio,scl-open-drain");
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pdata->scl_is_output_only =
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device_property_read_bool(dev, "i2c-gpio,scl-output-only");
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pdata->sda_is_output_only =
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device_property_read_bool(dev, "i2c-gpio,sda-output-only");
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pdata->sda_has_no_pullup =
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device_property_read_bool(dev, "i2c-gpio,sda-has-no-pullup");
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pdata->scl_has_no_pullup =
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device_property_read_bool(dev, "i2c-gpio,scl-has-no-pullup");
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}
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static struct gpio_desc *i2c_gpio_get_desc(struct device *dev,
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const char *con_id,
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unsigned int index,
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enum gpiod_flags gflags)
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{
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struct gpio_desc *retdesc;
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int ret;
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retdesc = devm_gpiod_get(dev, con_id, gflags);
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if (!IS_ERR(retdesc)) {
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dev_dbg(dev, "got GPIO from name %s\n", con_id);
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return retdesc;
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}
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retdesc = devm_gpiod_get_index(dev, NULL, index, gflags);
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if (!IS_ERR(retdesc)) {
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dev_dbg(dev, "got GPIO from index %u\n", index);
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return retdesc;
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}
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ret = PTR_ERR(retdesc);
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|
|
/* FIXME: hack in the old code, is this really necessary? */
|
||
|
|
if (ret == -EINVAL)
|
||
|
|
retdesc = ERR_PTR(-EPROBE_DEFER);
|
||
|
|
|
||
|
|
/* This happens if the GPIO driver is not yet probed, let's defer */
|
||
|
|
if (ret == -ENOENT)
|
||
|
|
retdesc = ERR_PTR(-EPROBE_DEFER);
|
||
|
|
|
||
|
|
if (PTR_ERR(retdesc) != -EPROBE_DEFER)
|
||
|
|
dev_err(dev, "error trying to get descriptor: %d\n", ret);
|
||
|
|
|
||
|
|
return retdesc;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int i2c_gpio_probe(struct platform_device *pdev)
|
||
|
|
{
|
||
|
|
struct i2c_gpio_private_data *priv;
|
||
|
|
struct i2c_gpio_platform_data *pdata;
|
||
|
|
struct i2c_algo_bit_data *bit_data;
|
||
|
|
struct i2c_adapter *adap;
|
||
|
|
struct device *dev = &pdev->dev;
|
||
|
|
struct fwnode_handle *fwnode = dev_fwnode(dev);
|
||
|
|
enum gpiod_flags gflags;
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
|
||
|
|
if (!priv)
|
||
|
|
return -ENOMEM;
|
||
|
|
|
||
|
|
adap = &priv->adap;
|
||
|
|
bit_data = &priv->bit_data;
|
||
|
|
pdata = &priv->pdata;
|
||
|
|
|
||
|
|
if (fwnode) {
|
||
|
|
i2c_gpio_get_properties(dev, pdata);
|
||
|
|
} else {
|
||
|
|
/*
|
||
|
|
* If all platform data settings are zero it is OK
|
||
|
|
* to not provide any platform data from the board.
|
||
|
|
*/
|
||
|
|
if (dev_get_platdata(dev))
|
||
|
|
memcpy(pdata, dev_get_platdata(dev), sizeof(*pdata));
|
||
|
|
}
|
||
|
|
|
||
|
|
/*
|
||
|
|
* First get the GPIO pins; if it fails, we'll defer the probe.
|
||
|
|
* If the SCL/SDA lines are marked "open drain" by platform data or
|
||
|
|
* device tree then this means that something outside of our control is
|
||
|
|
* marking these lines to be handled as open drain, and we should just
|
||
|
|
* handle them as we handle any other output. Else we enforce open
|
||
|
|
* drain as this is required for an I2C bus.
|
||
|
|
*/
|
||
|
|
if (pdata->sda_is_open_drain || pdata->sda_has_no_pullup)
|
||
|
|
gflags = GPIOD_OUT_HIGH;
|
||
|
|
else
|
||
|
|
gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
|
||
|
|
priv->sda = i2c_gpio_get_desc(dev, "sda", 0, gflags);
|
||
|
|
if (IS_ERR(priv->sda))
|
||
|
|
return PTR_ERR(priv->sda);
|
||
|
|
|
||
|
|
if (pdata->scl_is_open_drain || pdata->scl_has_no_pullup)
|
||
|
|
gflags = GPIOD_OUT_HIGH;
|
||
|
|
else
|
||
|
|
gflags = GPIOD_OUT_HIGH_OPEN_DRAIN;
|
||
|
|
priv->scl = i2c_gpio_get_desc(dev, "scl", 1, gflags);
|
||
|
|
if (IS_ERR(priv->scl))
|
||
|
|
return PTR_ERR(priv->scl);
|
||
|
|
|
||
|
|
if (gpiod_cansleep(priv->sda) || gpiod_cansleep(priv->scl))
|
||
|
|
dev_warn(dev, "Slow GPIO pins might wreak havoc into I2C/SMBus bus timing");
|
||
|
|
else
|
||
|
|
bit_data->can_do_atomic = true;
|
||
|
|
|
||
|
|
bit_data->setsda = i2c_gpio_setsda_val;
|
||
|
|
bit_data->setscl = i2c_gpio_setscl_val;
|
||
|
|
|
||
|
|
if (!pdata->scl_is_output_only)
|
||
|
|
bit_data->getscl = i2c_gpio_getscl;
|
||
|
|
if (!pdata->sda_is_output_only)
|
||
|
|
bit_data->getsda = i2c_gpio_getsda;
|
||
|
|
|
||
|
|
if (pdata->udelay)
|
||
|
|
bit_data->udelay = pdata->udelay;
|
||
|
|
else if (pdata->scl_is_output_only)
|
||
|
|
bit_data->udelay = 50; /* 10 kHz */
|
||
|
|
else
|
||
|
|
bit_data->udelay = 5; /* 100 kHz */
|
||
|
|
|
||
|
|
if (pdata->timeout)
|
||
|
|
bit_data->timeout = pdata->timeout;
|
||
|
|
else
|
||
|
|
bit_data->timeout = HZ / 10; /* 100 ms */
|
||
|
|
|
||
|
|
bit_data->data = priv;
|
||
|
|
|
||
|
|
adap->owner = THIS_MODULE;
|
||
|
|
if (fwnode)
|
||
|
|
strscpy(adap->name, dev_name(dev), sizeof(adap->name));
|
||
|
|
else
|
||
|
|
snprintf(adap->name, sizeof(adap->name), "i2c-gpio%d", pdev->id);
|
||
|
|
|
||
|
|
adap->algo_data = bit_data;
|
||
|
|
adap->class = I2C_CLASS_HWMON | I2C_CLASS_SPD;
|
||
|
|
adap->dev.parent = dev;
|
||
|
|
device_set_node(&adap->dev, fwnode);
|
||
|
|
|
||
|
|
adap->nr = pdev->id;
|
||
|
|
ret = i2c_bit_add_numbered_bus(adap);
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
platform_set_drvdata(pdev, priv);
|
||
|
|
|
||
|
|
/*
|
||
|
|
* FIXME: using global GPIO numbers is not helpful. If/when we
|
||
|
|
* get accessors to get the actual name of the GPIO line,
|
||
|
|
* from the descriptor, then provide that instead.
|
||
|
|
*/
|
||
|
|
dev_info(dev, "using lines %u (SDA) and %u (SCL%s)\n",
|
||
|
|
desc_to_gpio(priv->sda), desc_to_gpio(priv->scl),
|
||
|
|
pdata->scl_is_output_only
|
||
|
|
? ", no clock stretching" : "");
|
||
|
|
|
||
|
|
i2c_gpio_fault_injector_init(pdev);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static int i2c_gpio_remove(struct platform_device *pdev)
|
||
|
|
{
|
||
|
|
struct i2c_gpio_private_data *priv;
|
||
|
|
struct i2c_adapter *adap;
|
||
|
|
|
||
|
|
i2c_gpio_fault_injector_exit(pdev);
|
||
|
|
|
||
|
|
priv = platform_get_drvdata(pdev);
|
||
|
|
adap = &priv->adap;
|
||
|
|
|
||
|
|
i2c_del_adapter(adap);
|
||
|
|
|
||
|
|
return 0;
|
||
|
|
}
|
||
|
|
|
||
|
|
static const struct of_device_id i2c_gpio_dt_ids[] = {
|
||
|
|
{ .compatible = "i2c-gpio", },
|
||
|
|
{ /* sentinel */ }
|
||
|
|
};
|
||
|
|
|
||
|
|
MODULE_DEVICE_TABLE(of, i2c_gpio_dt_ids);
|
||
|
|
|
||
|
|
static const struct acpi_device_id i2c_gpio_acpi_match[] = {
|
||
|
|
{ "LOON0005" }, /* LoongArch */
|
||
|
|
{ }
|
||
|
|
};
|
||
|
|
MODULE_DEVICE_TABLE(acpi, i2c_gpio_acpi_match);
|
||
|
|
|
||
|
|
static struct platform_driver i2c_gpio_driver = {
|
||
|
|
.driver = {
|
||
|
|
.name = "i2c-gpio",
|
||
|
|
.of_match_table = i2c_gpio_dt_ids,
|
||
|
|
.acpi_match_table = i2c_gpio_acpi_match,
|
||
|
|
},
|
||
|
|
.probe = i2c_gpio_probe,
|
||
|
|
.remove = i2c_gpio_remove,
|
||
|
|
};
|
||
|
|
|
||
|
|
static int __init i2c_gpio_init(void)
|
||
|
|
{
|
||
|
|
int ret;
|
||
|
|
|
||
|
|
ret = platform_driver_register(&i2c_gpio_driver);
|
||
|
|
if (ret)
|
||
|
|
printk(KERN_ERR "i2c-gpio: probe failed: %d\n", ret);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
subsys_initcall(i2c_gpio_init);
|
||
|
|
|
||
|
|
static void __exit i2c_gpio_exit(void)
|
||
|
|
{
|
||
|
|
platform_driver_unregister(&i2c_gpio_driver);
|
||
|
|
}
|
||
|
|
module_exit(i2c_gpio_exit);
|
||
|
|
|
||
|
|
MODULE_AUTHOR("Haavard Skinnemoen (Atmel)");
|
||
|
|
MODULE_DESCRIPTION("Platform-independent bitbanging I2C driver");
|
||
|
|
MODULE_LICENSE("GPL v2");
|
||
|
|
MODULE_ALIAS("platform:i2c-gpio");
|