--- /dev/null
+/*
+ * 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);
+}
+
+/* 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;
+ int err;
+
+ err = si514_calc_muldiv(&settings, rate);
+ 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);
+
+ si514_enable_output(data, true);
+
+ return err;
+}
+
+static const struct clk_ops si514_clk_ops = {
+ .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;
+ struct clk *clk;
+ int err;
+
+ data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
+ if (!data)
+ return -ENOMEM;
+
+ init.ops = &si514_clk_ops;
+ init.flags = CLK_IS_ROOT;
+ 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);
+
+ clk = devm_clk_register(&client->dev, &data->hw);
+ if (IS_ERR(clk)) {
+ dev_err(&client->dev, "clock registration failed\n");
+ return PTR_ERR(clk);
+ }
+ err = of_clk_add_provider(client->dev.of_node, of_clk_src_simple_get,
+ clk);
+ 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");
projects / platform / kernel / linux-exynos.git / commitdiff