diff options
Diffstat (limited to 'drivers/clk/clk-si514.c')
| -rw-r--r-- | drivers/clk/clk-si514.c | 414 |
1 files changed, 414 insertions, 0 deletions
diff --git a/drivers/clk/clk-si514.c b/drivers/clk/clk-si514.c new file mode 100644 index 000000000..153b3a2b5 --- /dev/null +++ b/drivers/clk/clk-si514.c @@ -0,0 +1,414 @@ +/* + * Driver for Silicon Labs Si514 Programmable Oscillator + * + * Copyright (C) 2015 Topic Embedded Products + * + * Author: Mike Looijmans <mike.looijmans@topic.nl> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + */ + +#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 */ +#define SI514_REG_LP 0 +#define SI514_REG_M_FRAC1 5 +#define SI514_REG_M_FRAC2 6 +#define SI514_REG_M_FRAC3 7 +#define SI514_REG_M_INT_FRAC 8 +#define SI514_REG_M_INT 9 +#define SI514_REG_HS_DIV 10 +#define SI514_REG_LS_HS_DIV 11 +#define SI514_REG_OE_STATE 14 +#define SI514_REG_RESET 128 +#define SI514_REG_CONTROL 132 + +/* Register values */ +#define SI514_RESET_RST BIT(7) + +#define SI514_CONTROL_FCAL BIT(0) +#define SI514_CONTROL_OE BIT(2) + +#define SI514_MIN_FREQ 100000U +#define SI514_MAX_FREQ 250000000U + +#define FXO 31980000U + +#define FVCO_MIN 2080000000U +#define FVCO_MAX 2500000000U + +#define HS_DIV_MAX 1022 + +struct clk_si514 { + struct clk_hw hw; + struct regmap *regmap; + struct i2c_client *i2c_client; +}; +#define to_clk_si514(_hw) container_of(_hw, struct clk_si514, hw) + +/* Multiplier/divider settings */ +struct clk_si514_muldiv { + u32 m_frac; /* 29-bit Fractional part of multiplier M */ + u8 m_int; /* Integer part of multiplier M, 65..78 */ + u8 ls_div_bits; /* 2nd divider, as 2^x */ + u16 hs_div; /* 1st divider, must be even and 10<=x<=1022 */ +}; + +/* Enables or disables the output driver */ +static int si514_enable_output(struct clk_si514 *data, bool enable) +{ + return regmap_update_bits(data->regmap, SI514_REG_CONTROL, + SI514_CONTROL_OE, enable ? SI514_CONTROL_OE : 0); +} + +static int si514_prepare(struct clk_hw *hw) +{ + struct clk_si514 *data = to_clk_si514(hw); + + return si514_enable_output(data, true); +} + +static void si514_unprepare(struct clk_hw *hw) +{ + struct clk_si514 *data = to_clk_si514(hw); + + si514_enable_output(data, false); +} + +static int si514_is_prepared(struct clk_hw *hw) +{ + struct clk_si514 *data = to_clk_si514(hw); + unsigned int val; + int err; + + err = regmap_read(data->regmap, SI514_REG_CONTROL, &val); + if (err < 0) + return err; + + return !!(val & SI514_CONTROL_OE); +} + +/* Retrieve clock multiplier and dividers from hardware */ +static int si514_get_muldiv(struct clk_si514 *data, + struct clk_si514_muldiv *settings) +{ + int err; + u8 reg[7]; + + err = regmap_bulk_read(data->regmap, SI514_REG_M_FRAC1, + reg, ARRAY_SIZE(reg)); + if (err) + return err; + + settings->m_frac = reg[0] | reg[1] << 8 | reg[2] << 16 | + (reg[3] & 0x1F) << 24; + settings->m_int = (reg[4] & 0x3f) << 3 | reg[3] >> 5; + settings->ls_div_bits = (reg[6] >> 4) & 0x07; + settings->hs_div = (reg[6] & 0x03) << 8 | reg[5]; + return 0; +} + +static int si514_set_muldiv(struct clk_si514 *data, + struct clk_si514_muldiv *settings) +{ + u8 lp; + u8 reg[7]; + int err; + + /* Calculate LP1/LP2 according to table 13 in the datasheet */ + /* 65.259980246 */ + if (settings->m_int < 65 || + (settings->m_int == 65 && settings->m_frac <= 139575831)) + lp = 0x22; + /* 67.859763463 */ + else if (settings->m_int < 67 || + (settings->m_int == 67 && settings->m_frac <= 461581994)) + lp = 0x23; + /* 72.937624981 */ + else if (settings->m_int < 72 || + (settings->m_int == 72 && settings->m_frac <= 503383578)) + lp = 0x33; + /* 75.843265046 */ + else if (settings->m_int < 75 || + (settings->m_int == 75 && settings->m_frac <= 452724474)) + lp = 0x34; + else + lp = 0x44; + + err = regmap_write(data->regmap, SI514_REG_LP, lp); + if (err < 0) + return err; + + reg[0] = settings->m_frac; + reg[1] = settings->m_frac >> 8; + reg[2] = settings->m_frac >> 16; + reg[3] = settings->m_frac >> 24 | settings->m_int << 5; + reg[4] = settings->m_int >> 3; + reg[5] = settings->hs_div; + reg[6] = (settings->hs_div >> 8) | (settings->ls_div_bits << 4); + + err = regmap_bulk_write(data->regmap, SI514_REG_HS_DIV, reg + 5, 2); + if (err < 0) + return err; + /* + * Writing to SI514_REG_M_INT_FRAC triggers the clock change, so that + * must be written last + */ + return regmap_bulk_write(data->regmap, SI514_REG_M_FRAC1, reg, 5); +} + +/* Calculate divider settings for a given frequency */ +static int si514_calc_muldiv(struct clk_si514_muldiv *settings, + unsigned long frequency) +{ + u64 m; + u32 ls_freq; + u32 tmp; + u8 res; + + if ((frequency < SI514_MIN_FREQ) || (frequency > SI514_MAX_FREQ)) + return -EINVAL; + + /* Determine the minimum value of LS_DIV and resulting target freq. */ + ls_freq = frequency; + if (frequency >= (FVCO_MIN / HS_DIV_MAX)) + settings->ls_div_bits = 0; + else { + res = 1; + tmp = 2 * HS_DIV_MAX; + while (tmp <= (HS_DIV_MAX * 32)) { + if ((frequency * tmp) >= FVCO_MIN) + break; + ++res; + tmp <<= 1; + } + settings->ls_div_bits = res; + ls_freq = frequency << res; + } + + /* Determine minimum HS_DIV, round up to even number */ + settings->hs_div = DIV_ROUND_UP(FVCO_MIN >> 1, ls_freq) << 1; + + /* M = LS_DIV x HS_DIV x frequency / F_XO (in fixed-point) */ + m = ((u64)(ls_freq * settings->hs_div) << 29) + (FXO / 2); + do_div(m, FXO); + settings->m_frac = (u32)m & (BIT(29) - 1); + settings->m_int = (u32)(m >> 29); + + return 0; +} + +/* Calculate resulting frequency given the register settings */ +static unsigned long si514_calc_rate(struct clk_si514_muldiv *settings) +{ + u64 m = settings->m_frac | ((u64)settings->m_int << 29); + u32 d = settings->hs_div * BIT(settings->ls_div_bits); + + return ((u32)(((m * FXO) + (FXO / 2)) >> 29)) / d; +} + +static unsigned long si514_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_si514 *data = to_clk_si514(hw); + struct clk_si514_muldiv settings; + int err; + + err = si514_get_muldiv(data, &settings); + if (err) { + dev_err(&data->i2c_client->dev, "unable to retrieve settings\n"); + return 0; + } + + return si514_calc_rate(&settings); +} + +static long si514_round_rate(struct clk_hw *hw, unsigned long rate, + unsigned long *parent_rate) +{ + struct clk_si514_muldiv settings; + int err; + + if (!rate) + return 0; + + err = si514_calc_muldiv(&settings, rate); + if (err) + return err; + + return si514_calc_rate(&settings); +} + +/* + * Update output frequency for big frequency changes (> 1000 ppm). + * The chip supports <1000ppm changes "on the fly", we haven't implemented + * that here. + */ +static int si514_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_si514 *data = to_clk_si514(hw); + struct clk_si514_muldiv settings; + unsigned int old_oe_state; + int err; + + err = si514_calc_muldiv(&settings, rate); + if (err) + return err; + + err = regmap_read(data->regmap, SI514_REG_CONTROL, &old_oe_state); + if (err) + return err; + + si514_enable_output(data, false); + + err = si514_set_muldiv(data, &settings); + if (err < 0) + return err; /* Undefined state now, best to leave disabled */ + + /* Trigger calibration */ + err = regmap_write(data->regmap, SI514_REG_CONTROL, SI514_CONTROL_FCAL); + if (err < 0) + return err; + + /* Applying a new frequency can take up to 10ms */ + usleep_range(10000, 12000); + + if (old_oe_state & SI514_CONTROL_OE) + si514_enable_output(data, true); + + return err; +} + +static const struct clk_ops si514_clk_ops = { + .prepare = si514_prepare, + .unprepare = si514_unprepare, + .is_prepared = si514_is_prepared, + .recalc_rate = si514_recalc_rate, + .round_rate = si514_round_rate, + .set_rate = si514_set_rate, +}; + +static bool si514_regmap_is_volatile(struct device *dev, unsigned int reg) +{ + switch (reg) { + case SI514_REG_CONTROL: + case SI514_REG_RESET: + return true; + default: + return false; + } +} + +static bool si514_regmap_is_writeable(struct device *dev, unsigned int reg) +{ + switch (reg) { + case SI514_REG_LP: + case SI514_REG_M_FRAC1 ... SI514_REG_LS_HS_DIV: + case SI514_REG_OE_STATE: + case SI514_REG_RESET: + case SI514_REG_CONTROL: + return true; + default: + return false; + } +} + +static const struct regmap_config si514_regmap_config = { + .reg_bits = 8, + .val_bits = 8, + .cache_type = REGCACHE_RBTREE, + .max_register = SI514_REG_CONTROL, + .writeable_reg = si514_regmap_is_writeable, + .volatile_reg = si514_regmap_is_volatile, +}; + +static int si514_probe(struct i2c_client *client, + const struct i2c_device_id *id) +{ + struct clk_si514 *data; + struct clk_init_data init; + int err; + + data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL); + if (!data) + return -ENOMEM; + + init.ops = &si514_clk_ops; + init.flags = 0; + init.num_parents = 0; + data->hw.init = &init; + data->i2c_client = client; + + 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, &si514_regmap_config); + if (IS_ERR(data->regmap)) { + dev_err(&client->dev, "failed to allocate register map\n"); + return PTR_ERR(data->regmap); + } + + i2c_set_clientdata(client, data); + + err = devm_clk_hw_register(&client->dev, &data->hw); + if (err) { + dev_err(&client->dev, "clock registration failed\n"); + return err; + } + err = of_clk_add_hw_provider(client->dev.of_node, of_clk_hw_simple_get, + &data->hw); + if (err) { + dev_err(&client->dev, "unable to add clk provider\n"); + return err; + } + + return 0; +} + +static int si514_remove(struct i2c_client *client) +{ + of_clk_del_provider(client->dev.of_node); + return 0; +} + +static const struct i2c_device_id si514_id[] = { + { "si514", 0 }, + { } +}; +MODULE_DEVICE_TABLE(i2c, si514_id); + +static const struct of_device_id clk_si514_of_match[] = { + { .compatible = "silabs,si514" }, + { }, +}; +MODULE_DEVICE_TABLE(of, clk_si514_of_match); + +static struct i2c_driver si514_driver = { + .driver = { + .name = "si514", + .of_match_table = clk_si514_of_match, + }, + .probe = si514_probe, + .remove = si514_remove, + .id_table = si514_id, +}; +module_i2c_driver(si514_driver); + +MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>"); +MODULE_DESCRIPTION("Si514 driver"); +MODULE_LICENSE("GPL"); |