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-rw-r--r--drivers/clk/clk-si544.c530
1 files changed, 530 insertions, 0 deletions
diff --git a/drivers/clk/clk-si544.c b/drivers/clk/clk-si544.c
new file mode 100644
index 000000000..089786907
--- /dev/null
+++ b/drivers/clk/clk-si544.c
@@ -0,0 +1,530 @@
+// 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/math64.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)
+
+/* Range and interpretation of the adjustment value */
+#define DELTA_M_MAX 8161512
+#define DELTA_M_FRAC_NUM 19
+#define DELTA_M_FRAC_DEN 20000
+
+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
+ * @delta_m: Frequency shift for small -950..+950 ppm changes, 24 bit
+ */
+struct clk_si544_muldiv {
+ u32 fb_div_frac;
+ u16 fb_div_int;
+ u16 hs_div;
+ u8 ls_div_bits;
+ s32 delta_m;
+};
+
+/* 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);
+}
+
+static int si544_prepare(struct clk_hw *hw)
+{
+ struct clk_si544 *data = to_clk_si544(hw);
+
+ return si544_enable_output(data, true);
+}
+
+static void si544_unprepare(struct clk_hw *hw)
+{
+ struct clk_si544 *data = to_clk_si544(hw);
+
+ si544_enable_output(data, false);
+}
+
+static int si544_is_prepared(struct clk_hw *hw)
+{
+ struct clk_si544 *data = to_clk_si544(hw);
+ unsigned int val;
+ int err;
+
+ err = regmap_read(data->regmap, SI544_REG_OE_STATE, &val);
+ if (err < 0)
+ return err;
+
+ return !!(val & SI544_OE_STATE_ODC_OE);
+}
+
+/* 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;
+
+ err = regmap_bulk_read(data->regmap, SI544_REG_ADPLL_DELTA_M0, reg, 3);
+ if (err)
+ return err;
+
+ /* Interpret as 24-bit signed number */
+ settings->delta_m = reg[0] << 8 | reg[1] << 16 | reg[2] << 24;
+ settings->delta_m >>= 8;
+
+ return 0;
+}
+
+static int si544_set_delta_m(struct clk_si544 *data, s32 delta_m)
+{
+ u8 reg[3];
+
+ reg[0] = delta_m;
+ reg[1] = delta_m >> 8;
+ reg[2] = delta_m >> 16;
+
+ return regmap_bulk_write(data->regmap, SI544_REG_ADPLL_DELTA_M0,
+ reg, 3);
+}
+
+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;
+ vco += FXO / 2; /* Round to nearest multiple */
+ do_div(vco, FXO);
+ settings->fb_div_frac = vco;
+
+ /* Reset the frequency adjustment */
+ settings->delta_m = 0;
+
+ return 0;
+}
+
+/* Calculate resulting frequency given the register settings */
+static unsigned long si544_calc_center_rate(
+ const 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_calc_rate(const struct clk_si544_muldiv *settings)
+{
+ unsigned long rate = si544_calc_center_rate(settings);
+ s64 delta = (s64)rate * (DELTA_M_FRAC_NUM * settings->delta_m);
+
+ /*
+ * The clock adjustment is much smaller than 1 Hz, round to the
+ * nearest multiple. Apparently div64_s64 rounds towards zero, hence
+ * check the sign and adjust into the proper direction.
+ */
+ if (settings->delta_m < 0)
+ delta -= ((s64)DELTA_M_MAX * DELTA_M_FRAC_DEN) / 2;
+ else
+ delta += ((s64)DELTA_M_MAX * DELTA_M_FRAC_DEN) / 2;
+ delta = div64_s64(delta, ((s64)DELTA_M_MAX * DELTA_M_FRAC_DEN));
+
+ return rate + delta;
+}
+
+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);
+
+ if (!is_valid_frequency(data, rate))
+ return -EINVAL;
+
+ /* The accuracy is less than 1 Hz, so any rate is possible */
+ return rate;
+}
+
+/* Calculates the maximum "small" change, 950 * rate / 1000000 */
+static unsigned long si544_max_delta(unsigned long rate)
+{
+ u64 num = rate;
+
+ num *= DELTA_M_FRAC_NUM;
+ do_div(num, DELTA_M_FRAC_DEN);
+
+ return num;
+}
+
+static s32 si544_calc_delta(s32 delta, s32 max_delta)
+{
+ s64 n = (s64)delta * DELTA_M_MAX;
+
+ return div_s64(n, max_delta);
+}
+
+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;
+ unsigned long center;
+ long max_delta;
+ long delta;
+ unsigned int old_oe_state;
+ int err;
+
+ if (!is_valid_frequency(data, rate))
+ return -EINVAL;
+
+ /* Try using the frequency adjustment feature for a <= 950ppm change */
+ err = si544_get_muldiv(data, &settings);
+ if (err)
+ return err;
+
+ center = si544_calc_center_rate(&settings);
+ max_delta = si544_max_delta(center);
+ delta = rate - center;
+
+ if (abs(delta) <= max_delta)
+ return si544_set_delta_m(data,
+ si544_calc_delta(delta, max_delta));
+
+ /* Too big for the delta adjustment, need to reprogram */
+ err = si544_calc_muldiv(&settings, rate);
+ if (err)
+ return err;
+
+ err = regmap_read(data->regmap, SI544_REG_OE_STATE, &old_oe_state);
+ 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_delta_m(data, settings.delta_m);
+ 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);
+
+ if (old_oe_state & SI544_OE_STATE_ODC_OE)
+ si544_enable_output(data, true);
+
+ return err;
+}
+
+static const struct clk_ops si544_clk_ops = {
+ .prepare = si544_prepare,
+ .unprepare = si544_unprepare,
+ .is_prepared = si544_is_prepared,
+ .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 const struct i2c_device_id si544_id[] = {
+ { "si544a", si544a },
+ { "si544b", si544b },
+ { "si544c", si544c },
+ { }
+};
+MODULE_DEVICE_TABLE(i2c, si544_id);
+
+static int si544_probe(struct i2c_client *client)
+{
+ struct clk_si544 *data;
+ struct clk_init_data init;
+ const struct i2c_device_id *id = i2c_match_id(si544_id, client);
+ 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 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_new = 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");
generated by cgit v1.2.3 (git 2.39.1) at 2024-11-27 02:49:45 +0000