| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Driver for Silicon Labs Si544 Programmable Oscillator |
| * Copyright (C) 2018 Topic Embedded Products |
| * Author: Mike Looijmans <mike.looijmans@topic.nl> |
| */ |
| |
| #include <linux/clk-provider.h> |
| #include <linux/delay.h> |
| #include <linux/module.h> |
| #include <linux/i2c.h> |
| #include <linux/regmap.h> |
| #include <linux/slab.h> |
| |
| /* I2C registers (decimal as in datasheet) */ |
| #define SI544_REG_CONTROL 7 |
| #define SI544_REG_OE_STATE 17 |
| #define SI544_REG_HS_DIV 23 |
| #define SI544_REG_LS_HS_DIV 24 |
| #define SI544_REG_FBDIV0 26 |
| #define SI544_REG_FBDIV8 27 |
| #define SI544_REG_FBDIV16 28 |
| #define SI544_REG_FBDIV24 29 |
| #define SI544_REG_FBDIV32 30 |
| #define SI544_REG_FBDIV40 31 |
| #define SI544_REG_FCAL_OVR 69 |
| #define SI544_REG_ADPLL_DELTA_M0 231 |
| #define SI544_REG_ADPLL_DELTA_M8 232 |
| #define SI544_REG_ADPLL_DELTA_M16 233 |
| #define SI544_REG_PAGE_SELECT 255 |
| |
| /* Register values */ |
| #define SI544_CONTROL_RESET BIT(7) |
| #define SI544_CONTROL_MS_ICAL2 BIT(3) |
| |
| #define SI544_OE_STATE_ODC_OE BIT(0) |
| |
| /* Max freq depends on speed grade */ |
| #define SI544_MIN_FREQ 200000U |
| |
| /* Si544 Internal oscilator runs at 55.05 MHz */ |
| #define FXO 55050000U |
| |
| /* VCO range is 10.8 .. 12.1 GHz, max depends on speed grade */ |
| #define FVCO_MIN 10800000000ULL |
| |
| #define HS_DIV_MAX 2046 |
| #define HS_DIV_MAX_ODD 33 |
| |
| /* Lowest frequency synthesizeable using only the HS divider */ |
| #define MIN_HSDIV_FREQ (FVCO_MIN / HS_DIV_MAX) |
| |
| enum si544_speed_grade { |
| si544a, |
| si544b, |
| si544c, |
| }; |
| |
| struct clk_si544 { |
| struct clk_hw hw; |
| struct regmap *regmap; |
| struct i2c_client *i2c_client; |
| enum si544_speed_grade speed_grade; |
| }; |
| #define to_clk_si544(_hw) container_of(_hw, struct clk_si544, hw) |
| |
| /** |
| * struct clk_si544_muldiv - Multiplier/divider settings |
| * @fb_div_frac: integer part of feedback divider (32 bits) |
| * @fb_div_int: fractional part of feedback divider (11 bits) |
| * @hs_div: 1st divider, 5..2046, must be even when >33 |
| * @ls_div_bits: 2nd divider, as 2^x, range 0..5 |
| * If ls_div_bits is non-zero, hs_div must be even |
| */ |
| struct clk_si544_muldiv { |
| u32 fb_div_frac; |
| u16 fb_div_int; |
| u16 hs_div; |
| u8 ls_div_bits; |
| }; |
| |
| /* Enables or disables the output driver */ |
| static int si544_enable_output(struct clk_si544 *data, bool enable) |
| { |
| return regmap_update_bits(data->regmap, SI544_REG_OE_STATE, |
| SI544_OE_STATE_ODC_OE, enable ? SI544_OE_STATE_ODC_OE : 0); |
| } |
| |
| /* Retrieve clock multiplier and dividers from hardware */ |
| static int si544_get_muldiv(struct clk_si544 *data, |
| struct clk_si544_muldiv *settings) |
| { |
| int err; |
| u8 reg[6]; |
| |
| err = regmap_bulk_read(data->regmap, SI544_REG_HS_DIV, reg, 2); |
| if (err) |
| return err; |
| |
| settings->ls_div_bits = (reg[1] >> 4) & 0x07; |
| settings->hs_div = (reg[1] & 0x07) << 8 | reg[0]; |
| |
| err = regmap_bulk_read(data->regmap, SI544_REG_FBDIV0, reg, 6); |
| if (err) |
| return err; |
| |
| settings->fb_div_int = reg[4] | (reg[5] & 0x07) << 8; |
| settings->fb_div_frac = reg[0] | reg[1] << 8 | reg[2] << 16 | |
| reg[3] << 24; |
| return 0; |
| } |
| |
| static int si544_set_muldiv(struct clk_si544 *data, |
| struct clk_si544_muldiv *settings) |
| { |
| int err; |
| u8 reg[6]; |
| |
| reg[0] = settings->hs_div; |
| reg[1] = settings->hs_div >> 8 | settings->ls_div_bits << 4; |
| |
| err = regmap_bulk_write(data->regmap, SI544_REG_HS_DIV, reg, 2); |
| if (err < 0) |
| return err; |
| |
| reg[0] = settings->fb_div_frac; |
| reg[1] = settings->fb_div_frac >> 8; |
| reg[2] = settings->fb_div_frac >> 16; |
| reg[3] = settings->fb_div_frac >> 24; |
| reg[4] = settings->fb_div_int; |
| reg[5] = settings->fb_div_int >> 8; |
| |
| /* |
| * Writing to SI544_REG_FBDIV40 triggers the clock change, so that |
| * must be written last |
| */ |
| return regmap_bulk_write(data->regmap, SI544_REG_FBDIV0, reg, 6); |
| } |
| |
| static bool is_valid_frequency(const struct clk_si544 *data, |
| unsigned long frequency) |
| { |
| unsigned long max_freq = 0; |
| |
| if (frequency < SI544_MIN_FREQ) |
| return false; |
| |
| switch (data->speed_grade) { |
| case si544a: |
| max_freq = 1500000000; |
| break; |
| case si544b: |
| max_freq = 800000000; |
| break; |
| case si544c: |
| max_freq = 350000000; |
| break; |
| } |
| |
| return frequency <= max_freq; |
| } |
| |
| /* Calculate divider settings for a given frequency */ |
| static int si544_calc_muldiv(struct clk_si544_muldiv *settings, |
| unsigned long frequency) |
| { |
| u64 vco; |
| u32 ls_freq; |
| u32 tmp; |
| u8 res; |
| |
| /* Determine the minimum value of LS_DIV and resulting target freq. */ |
| ls_freq = frequency; |
| settings->ls_div_bits = 0; |
| |
| if (frequency >= MIN_HSDIV_FREQ) { |
| settings->ls_div_bits = 0; |
| } else { |
| res = 1; |
| tmp = 2 * HS_DIV_MAX; |
| while (tmp <= (HS_DIV_MAX * 32)) { |
| if (((u64)frequency * tmp) >= FVCO_MIN) |
| break; |
| ++res; |
| tmp <<= 1; |
| } |
| settings->ls_div_bits = res; |
| ls_freq = frequency << res; |
| } |
| |
| /* Determine minimum HS_DIV by rounding up */ |
| vco = FVCO_MIN + ls_freq - 1; |
| do_div(vco, ls_freq); |
| settings->hs_div = vco; |
| |
| /* round up to even number when required */ |
| if ((settings->hs_div & 1) && |
| (settings->hs_div > HS_DIV_MAX_ODD || settings->ls_div_bits)) |
| ++settings->hs_div; |
| |
| /* Calculate VCO frequency (in 10..12GHz range) */ |
| vco = (u64)ls_freq * settings->hs_div; |
| |
| /* Calculate the integer part of the feedback divider */ |
| tmp = do_div(vco, FXO); |
| settings->fb_div_int = vco; |
| |
| /* And the fractional bits using the remainder */ |
| vco = (u64)tmp << 32; |
| do_div(vco, FXO); |
| settings->fb_div_frac = vco; |
| |
| return 0; |
| } |
| |
| /* Calculate resulting frequency given the register settings */ |
| static unsigned long si544_calc_rate(struct clk_si544_muldiv *settings) |
| { |
| u32 d = settings->hs_div * BIT(settings->ls_div_bits); |
| u64 vco; |
| |
| /* Calculate VCO from the fractional part */ |
| vco = (u64)settings->fb_div_frac * FXO; |
| vco += (FXO / 2); |
| vco >>= 32; |
| |
| /* Add the integer part of the VCO frequency */ |
| vco += (u64)settings->fb_div_int * FXO; |
| |
| /* Apply divider to obtain the generated frequency */ |
| do_div(vco, d); |
| |
| return vco; |
| } |
| |
| static unsigned long si544_recalc_rate(struct clk_hw *hw, |
| unsigned long parent_rate) |
| { |
| struct clk_si544 *data = to_clk_si544(hw); |
| struct clk_si544_muldiv settings; |
| int err; |
| |
| err = si544_get_muldiv(data, &settings); |
| if (err) |
| return 0; |
| |
| return si544_calc_rate(&settings); |
| } |
| |
| static long si544_round_rate(struct clk_hw *hw, unsigned long rate, |
| unsigned long *parent_rate) |
| { |
| struct clk_si544 *data = to_clk_si544(hw); |
| struct clk_si544_muldiv settings; |
| int err; |
| |
| if (!is_valid_frequency(data, rate)) |
| return -EINVAL; |
| |
| err = si544_calc_muldiv(&settings, rate); |
| if (err) |
| return err; |
| |
| return si544_calc_rate(&settings); |
| } |
| |
| /* |
| * Update output frequency for "big" frequency changes |
| */ |
| static int si544_set_rate(struct clk_hw *hw, unsigned long rate, |
| unsigned long parent_rate) |
| { |
| struct clk_si544 *data = to_clk_si544(hw); |
| struct clk_si544_muldiv settings; |
| int err; |
| |
| if (!is_valid_frequency(data, rate)) |
| return -EINVAL; |
| |
| err = si544_calc_muldiv(&settings, rate); |
| if (err) |
| return err; |
| |
| si544_enable_output(data, false); |
| |
| /* Allow FCAL for this frequency update */ |
| err = regmap_write(data->regmap, SI544_REG_FCAL_OVR, 0); |
| if (err < 0) |
| return err; |
| |
| |
| err = si544_set_muldiv(data, &settings); |
| if (err < 0) |
| return err; /* Undefined state now, best to leave disabled */ |
| |
| /* Trigger calibration */ |
| err = regmap_write(data->regmap, SI544_REG_CONTROL, |
| SI544_CONTROL_MS_ICAL2); |
| if (err < 0) |
| return err; |
| |
| /* Applying a new frequency can take up to 10ms */ |
| usleep_range(10000, 12000); |
| |
| si544_enable_output(data, true); |
| |
| return err; |
| } |
| |
| static const struct clk_ops si544_clk_ops = { |
| .recalc_rate = si544_recalc_rate, |
| .round_rate = si544_round_rate, |
| .set_rate = si544_set_rate, |
| }; |
| |
| static bool si544_regmap_is_volatile(struct device *dev, unsigned int reg) |
| { |
| switch (reg) { |
| case SI544_REG_CONTROL: |
| case SI544_REG_FCAL_OVR: |
| return true; |
| default: |
| return false; |
| } |
| } |
| |
| static const struct regmap_config si544_regmap_config = { |
| .reg_bits = 8, |
| .val_bits = 8, |
| .cache_type = REGCACHE_RBTREE, |
| .max_register = SI544_REG_PAGE_SELECT, |
| .volatile_reg = si544_regmap_is_volatile, |
| }; |
| |
| static int si544_probe(struct i2c_client *client, |
| const struct i2c_device_id *id) |
| { |
| struct clk_si544 *data; |
| struct clk_init_data init; |
| int err; |
| |
| data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); |
| if (!data) |
| return -ENOMEM; |
| |
| init.ops = &si544_clk_ops; |
| init.flags = 0; |
| init.num_parents = 0; |
| data->hw.init = &init; |
| data->i2c_client = client; |
| data->speed_grade = id->driver_data; |
| |
| if (of_property_read_string(client->dev.of_node, "clock-output-names", |
| &init.name)) |
| init.name = client->dev.of_node->name; |
| |
| data->regmap = devm_regmap_init_i2c(client, &si544_regmap_config); |
| if (IS_ERR(data->regmap)) |
| return PTR_ERR(data->regmap); |
| |
| i2c_set_clientdata(client, data); |
| |
| /* Select page 0, just to be sure, there appear to be no more */ |
| err = regmap_write(data->regmap, SI544_REG_PAGE_SELECT, 0); |
| if (err < 0) |
| return err; |
| |
| err = devm_clk_hw_register(&client->dev, &data->hw); |
| if (err) { |
| dev_err(&client->dev, "clock registration failed\n"); |
| return err; |
| } |
| err = devm_of_clk_add_hw_provider(&client->dev, of_clk_hw_simple_get, |
| &data->hw); |
| if (err) { |
| dev_err(&client->dev, "unable to add clk provider\n"); |
| return err; |
| } |
| |
| return 0; |
| } |
| |
| static const struct i2c_device_id si544_id[] = { |
| { "si544a", si544a }, |
| { "si544b", si544b }, |
| { "si544c", si544c }, |
| { } |
| }; |
| MODULE_DEVICE_TABLE(i2c, si544_id); |
| |
| static const struct of_device_id clk_si544_of_match[] = { |
| { .compatible = "silabs,si544a" }, |
| { .compatible = "silabs,si544b" }, |
| { .compatible = "silabs,si544c" }, |
| { }, |
| }; |
| MODULE_DEVICE_TABLE(of, clk_si544_of_match); |
| |
| static struct i2c_driver si544_driver = { |
| .driver = { |
| .name = "si544", |
| .of_match_table = clk_si544_of_match, |
| }, |
| .probe = si544_probe, |
| .id_table = si544_id, |
| }; |
| module_i2c_driver(si544_driver); |
| |
| MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>"); |
| MODULE_DESCRIPTION("Si544 driver"); |
| MODULE_LICENSE("GPL"); |