530 lines
13 KiB
C
530 lines
13 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Driver for Silicon Labs Si570/Si571 Programmable XO/VCXO
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*
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* Copyright (C) 2010, 2011 Ericsson AB.
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* Copyright (C) 2011 Guenter Roeck.
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* Copyright (C) 2011 - 2021 Xilinx Inc.
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*
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* Author: Guenter Roeck <guenter.roeck@ericsson.com>
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* Sören Brinkmann <soren.brinkmann@xilinx.com>
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*/
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#include <linux/clk.h>
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#include <linux/clk-provider.h>
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#include <linux/delay.h>
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#include <linux/module.h>
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#include <linux/i2c.h>
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#include <linux/regmap.h>
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#include <linux/slab.h>
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/* Si570 registers */
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#define SI570_REG_HS_N1 7
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#define SI570_REG_N1_RFREQ0 8
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#define SI570_REG_RFREQ1 9
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#define SI570_REG_RFREQ2 10
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#define SI570_REG_RFREQ3 11
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#define SI570_REG_RFREQ4 12
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#define SI570_REG_CONTROL 135
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#define SI570_REG_FREEZE_DCO 137
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#define SI570_DIV_OFFSET_7PPM 6
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#define HS_DIV_SHIFT 5
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#define HS_DIV_MASK 0xe0
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#define HS_DIV_OFFSET 4
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#define N1_6_2_MASK 0x1f
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#define N1_1_0_MASK 0xc0
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#define RFREQ_37_32_MASK 0x3f
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#define SI570_MIN_FREQ 10000000L
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#define SI570_MAX_FREQ 1417500000L
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#define SI598_MAX_FREQ 525000000L
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#define FDCO_MIN 4850000000LL
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#define FDCO_MAX 5670000000LL
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#define SI570_CNTRL_RECALL (1 << 0)
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#define SI570_CNTRL_FREEZE_M (1 << 5)
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#define SI570_CNTRL_NEWFREQ (1 << 6)
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#define SI570_FREEZE_DCO (1 << 4)
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/**
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* struct clk_si570:
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* @hw: Clock hw struct
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* @regmap: Device's regmap
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* @div_offset: Rgister offset for dividers
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* @max_freq: Maximum frequency for this device
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* @fxtal: Factory xtal frequency
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* @n1: Clock divider N1
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* @hs_div: Clock divider HSDIV
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* @rfreq: Clock multiplier RFREQ
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* @frequency: Current output frequency
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* @i2c_client: I2C client pointer
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*/
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struct clk_si570 {
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struct clk_hw hw;
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struct regmap *regmap;
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unsigned int div_offset;
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u64 max_freq;
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u64 fxtal;
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unsigned int n1;
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unsigned int hs_div;
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u64 rfreq;
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u64 frequency;
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struct i2c_client *i2c_client;
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};
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#define to_clk_si570(_hw) container_of(_hw, struct clk_si570, hw)
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enum clk_si570_variant {
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si57x,
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si59x
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};
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/**
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* si570_get_divs() - Read clock dividers from HW
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* @data: Pointer to struct clk_si570
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* @rfreq: Fractional multiplier (output)
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* @n1: Divider N1 (output)
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* @hs_div: Divider HSDIV (output)
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* Returns 0 on success, negative errno otherwise.
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*
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* Retrieve clock dividers and multipliers from the HW.
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*/
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static int si570_get_divs(struct clk_si570 *data, u64 *rfreq,
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unsigned int *n1, unsigned int *hs_div)
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{
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int err;
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u8 reg[6];
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u64 tmp;
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err = regmap_bulk_read(data->regmap, SI570_REG_HS_N1 + data->div_offset,
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reg, ARRAY_SIZE(reg));
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if (err)
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return err;
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*hs_div = ((reg[0] & HS_DIV_MASK) >> HS_DIV_SHIFT) + HS_DIV_OFFSET;
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*n1 = ((reg[0] & N1_6_2_MASK) << 2) + ((reg[1] & N1_1_0_MASK) >> 6) + 1;
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/* Handle invalid cases */
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if (*n1 > 1)
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*n1 &= ~1;
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tmp = reg[1] & RFREQ_37_32_MASK;
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tmp = (tmp << 8) + reg[2];
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tmp = (tmp << 8) + reg[3];
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tmp = (tmp << 8) + reg[4];
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tmp = (tmp << 8) + reg[5];
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*rfreq = tmp;
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return 0;
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}
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/**
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* si570_get_defaults() - Get default values
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* @data: Driver data structure
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* @fout: Factory frequency output
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* @skip_recall: If true, don't recall NVM into RAM
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* Returns 0 on success, negative errno otherwise.
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*/
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static int si570_get_defaults(struct clk_si570 *data, u64 fout,
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bool skip_recall)
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{
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int err;
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u64 fdco;
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if (!skip_recall)
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regmap_write(data->regmap, SI570_REG_CONTROL,
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SI570_CNTRL_RECALL);
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err = si570_get_divs(data, &data->rfreq, &data->n1, &data->hs_div);
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if (err)
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return err;
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/*
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* Accept optional precision loss to avoid arithmetic overflows.
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* Acceptable per Silicon Labs Application Note AN334.
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*/
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fdco = fout * data->n1 * data->hs_div;
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if (fdco >= (1LL << 36))
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data->fxtal = div64_u64(fdco << 24, data->rfreq >> 4);
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else
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data->fxtal = div64_u64(fdco << 28, data->rfreq);
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data->frequency = fout;
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return 0;
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}
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/**
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* si570_update_rfreq() - Update clock multiplier
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* @data: Driver data structure
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* Passes on regmap_bulk_write() return value.
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*/
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static int si570_update_rfreq(struct clk_si570 *data)
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{
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u8 reg[5];
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reg[0] = ((data->n1 - 1) << 6) |
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((data->rfreq >> 32) & RFREQ_37_32_MASK);
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reg[1] = (data->rfreq >> 24) & 0xff;
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reg[2] = (data->rfreq >> 16) & 0xff;
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reg[3] = (data->rfreq >> 8) & 0xff;
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reg[4] = data->rfreq & 0xff;
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return regmap_bulk_write(data->regmap, SI570_REG_N1_RFREQ0 +
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data->div_offset, reg, ARRAY_SIZE(reg));
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}
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/**
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* si570_calc_divs() - Caluclate clock dividers
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* @frequency: Target frequency
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* @data: Driver data structure
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* @out_rfreq: RFREG fractional multiplier (output)
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* @out_n1: Clock divider N1 (output)
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* @out_hs_div: Clock divider HSDIV (output)
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* Returns 0 on success, negative errno otherwise.
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*
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* Calculate the clock dividers (@out_hs_div, @out_n1) and clock multiplier
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* (@out_rfreq) for a given target @frequency.
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*/
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static int si570_calc_divs(unsigned long frequency, struct clk_si570 *data,
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u64 *out_rfreq, unsigned int *out_n1, unsigned int *out_hs_div)
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{
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int i;
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unsigned int n1, hs_div;
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u64 fdco, best_fdco = ULLONG_MAX;
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static const uint8_t si570_hs_div_values[] = { 11, 9, 7, 6, 5, 4 };
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for (i = 0; i < ARRAY_SIZE(si570_hs_div_values); i++) {
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hs_div = si570_hs_div_values[i];
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/* Calculate lowest possible value for n1 */
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n1 = div_u64(div_u64(FDCO_MIN, hs_div), frequency);
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if (!n1 || (n1 & 1))
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n1++;
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while (n1 <= 128) {
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fdco = (u64)frequency * (u64)hs_div * (u64)n1;
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if (fdco > FDCO_MAX)
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break;
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if (fdco >= FDCO_MIN && fdco < best_fdco) {
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*out_n1 = n1;
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*out_hs_div = hs_div;
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*out_rfreq = div64_u64(fdco << 28, data->fxtal);
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best_fdco = fdco;
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}
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n1 += (n1 == 1 ? 1 : 2);
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}
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}
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if (best_fdco == ULLONG_MAX)
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return -EINVAL;
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return 0;
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}
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static unsigned long si570_recalc_rate(struct clk_hw *hw,
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unsigned long parent_rate)
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{
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int err;
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u64 rfreq, rate;
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unsigned int n1, hs_div;
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struct clk_si570 *data = to_clk_si570(hw);
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err = si570_get_divs(data, &rfreq, &n1, &hs_div);
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if (err) {
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dev_err(&data->i2c_client->dev, "unable to recalc rate\n");
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return data->frequency;
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}
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rfreq = div_u64(rfreq, hs_div * n1);
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rate = (data->fxtal * rfreq) >> 28;
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return rate;
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}
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static long si570_round_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long *parent_rate)
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{
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int err;
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u64 rfreq;
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unsigned int n1, hs_div;
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struct clk_si570 *data = to_clk_si570(hw);
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if (!rate)
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return 0;
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if (div64_u64(abs(rate - data->frequency) * 10000LL,
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data->frequency) < 35) {
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rfreq = div64_u64((data->rfreq * rate) +
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div64_u64(data->frequency, 2), data->frequency);
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n1 = data->n1;
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hs_div = data->hs_div;
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} else {
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err = si570_calc_divs(rate, data, &rfreq, &n1, &hs_div);
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if (err) {
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dev_err(&data->i2c_client->dev,
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"unable to round rate\n");
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return 0;
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}
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}
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return rate;
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}
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/**
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* si570_set_frequency() - Adjust output frequency
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* @data: Driver data structure
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* @frequency: Target frequency
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* Returns 0 on success.
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*
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* Update output frequency for big frequency changes (> 3,500 ppm).
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*/
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static int si570_set_frequency(struct clk_si570 *data, unsigned long frequency)
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{
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int err;
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err = si570_calc_divs(frequency, data, &data->rfreq, &data->n1,
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&data->hs_div);
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if (err)
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return err;
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/*
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* The DCO reg should be accessed with a read-modify-write operation
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* per AN334
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*/
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regmap_write(data->regmap, SI570_REG_FREEZE_DCO, SI570_FREEZE_DCO);
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regmap_write(data->regmap, SI570_REG_HS_N1 + data->div_offset,
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((data->hs_div - HS_DIV_OFFSET) << HS_DIV_SHIFT) |
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(((data->n1 - 1) >> 2) & N1_6_2_MASK));
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si570_update_rfreq(data);
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regmap_write(data->regmap, SI570_REG_FREEZE_DCO, 0);
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regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_NEWFREQ);
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/* Applying a new frequency can take up to 10ms */
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usleep_range(10000, 12000);
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return 0;
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}
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/**
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* si570_set_frequency_small() - Adjust output frequency
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* @data: Driver data structure
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* @frequency: Target frequency
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* Returns 0 on success.
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*
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* Update output frequency for small frequency changes (< 3,500 ppm).
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*/
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static int si570_set_frequency_small(struct clk_si570 *data,
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unsigned long frequency)
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{
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/*
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* This is a re-implementation of DIV_ROUND_CLOSEST
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* using the div64_u64 function lieu of letting the compiler
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* insert EABI calls
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*/
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data->rfreq = div64_u64((data->rfreq * frequency) +
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div_u64(data->frequency, 2), data->frequency);
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regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_FREEZE_M);
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si570_update_rfreq(data);
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regmap_write(data->regmap, SI570_REG_CONTROL, 0);
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/* Applying a new frequency (small change) can take up to 100us */
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usleep_range(100, 200);
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return 0;
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}
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static int si570_set_rate(struct clk_hw *hw, unsigned long rate,
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unsigned long parent_rate)
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{
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struct clk_si570 *data = to_clk_si570(hw);
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struct i2c_client *client = data->i2c_client;
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int err;
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if (rate < SI570_MIN_FREQ || rate > data->max_freq) {
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dev_err(&client->dev,
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"requested frequency %lu Hz is out of range\n", rate);
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return -EINVAL;
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}
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if (div64_u64(abs(rate - data->frequency) * 10000LL,
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data->frequency) < 35)
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err = si570_set_frequency_small(data, rate);
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else
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err = si570_set_frequency(data, rate);
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if (err)
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return err;
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data->frequency = rate;
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return 0;
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}
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static const struct clk_ops si570_clk_ops = {
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.recalc_rate = si570_recalc_rate,
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.round_rate = si570_round_rate,
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.set_rate = si570_set_rate,
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};
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static bool si570_regmap_is_volatile(struct device *dev, unsigned int reg)
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{
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switch (reg) {
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case SI570_REG_CONTROL:
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return true;
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default:
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return false;
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}
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}
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static bool si570_regmap_is_writeable(struct device *dev, unsigned int reg)
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{
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switch (reg) {
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case SI570_REG_HS_N1 ... (SI570_REG_RFREQ4 + SI570_DIV_OFFSET_7PPM):
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case SI570_REG_CONTROL:
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case SI570_REG_FREEZE_DCO:
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return true;
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default:
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return false;
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}
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}
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static const struct regmap_config si570_regmap_config = {
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.reg_bits = 8,
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.val_bits = 8,
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.cache_type = REGCACHE_RBTREE,
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.max_register = 137,
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.writeable_reg = si570_regmap_is_writeable,
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.volatile_reg = si570_regmap_is_volatile,
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};
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static const struct i2c_device_id si570_id[] = {
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{ "si570", si57x },
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{ "si571", si57x },
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{ "si598", si59x },
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{ "si599", si59x },
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{ }
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};
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MODULE_DEVICE_TABLE(i2c, si570_id);
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static int si570_probe(struct i2c_client *client)
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{
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struct clk_si570 *data;
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struct clk_init_data init;
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const struct i2c_device_id *id = i2c_match_id(si570_id, client);
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u32 initial_fout, factory_fout, stability;
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bool skip_recall;
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int err;
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enum clk_si570_variant variant = id->driver_data;
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data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
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if (!data)
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return -ENOMEM;
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init.ops = &si570_clk_ops;
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init.flags = 0;
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init.num_parents = 0;
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data->hw.init = &init;
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data->i2c_client = client;
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if (variant == si57x) {
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err = of_property_read_u32(client->dev.of_node,
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"temperature-stability", &stability);
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if (err) {
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dev_err(&client->dev,
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"'temperature-stability' property missing\n");
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return err;
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}
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/* adjust register offsets for 7ppm devices */
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if (stability == 7)
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data->div_offset = SI570_DIV_OFFSET_7PPM;
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data->max_freq = SI570_MAX_FREQ;
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} else {
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data->max_freq = SI598_MAX_FREQ;
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}
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if (of_property_read_string(client->dev.of_node, "clock-output-names",
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&init.name))
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init.name = client->dev.of_node->name;
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err = of_property_read_u32(client->dev.of_node, "factory-fout",
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&factory_fout);
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if (err) {
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dev_err(&client->dev, "'factory-fout' property missing\n");
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return err;
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}
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skip_recall = of_property_read_bool(client->dev.of_node,
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"silabs,skip-recall");
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data->regmap = devm_regmap_init_i2c(client, &si570_regmap_config);
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if (IS_ERR(data->regmap)) {
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dev_err(&client->dev, "failed to allocate register map\n");
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return PTR_ERR(data->regmap);
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}
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i2c_set_clientdata(client, data);
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err = si570_get_defaults(data, factory_fout, skip_recall);
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if (err)
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return err;
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err = devm_clk_hw_register(&client->dev, &data->hw);
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if (err) {
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dev_err(&client->dev, "clock registration failed\n");
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return err;
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}
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err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get,
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&data->hw);
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if (err) {
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dev_err(&client->dev, "unable to add clk provider\n");
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return err;
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}
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/* Read the requested initial output frequency from device tree */
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if (!of_property_read_u32(client->dev.of_node, "clock-frequency",
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&initial_fout)) {
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err = clk_set_rate(data->hw.clk, initial_fout);
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if (err) {
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of_clk_del_provider(client->dev.of_node);
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return err;
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}
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}
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/* Display a message indicating that we've successfully registered */
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dev_info(&client->dev, "registered, current frequency %llu Hz\n",
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data->frequency);
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return 0;
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}
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static void si570_remove(struct i2c_client *client)
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{
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of_clk_del_provider(client->dev.of_node);
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}
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|
|
|
static const struct of_device_id clk_si570_of_match[] = {
|
|
{ .compatible = "silabs,si570" },
|
|
{ .compatible = "silabs,si571" },
|
|
{ .compatible = "silabs,si598" },
|
|
{ .compatible = "silabs,si599" },
|
|
{ },
|
|
};
|
|
MODULE_DEVICE_TABLE(of, clk_si570_of_match);
|
|
|
|
static struct i2c_driver si570_driver = {
|
|
.driver = {
|
|
.name = "si570",
|
|
.of_match_table = clk_si570_of_match,
|
|
},
|
|
.probe_new = si570_probe,
|
|
.remove = si570_remove,
|
|
.id_table = si570_id,
|
|
};
|
|
module_i2c_driver(si570_driver);
|
|
|
|
MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
|
|
MODULE_AUTHOR("Soeren Brinkmann <soren.brinkmann@xilinx.com>");
|
|
MODULE_DESCRIPTION("Si570 driver");
|
|
MODULE_LICENSE("GPL");
|