1 files changed, 379 insertions, 0 deletions
diff --git a/drivers/clk/clk-si514.c b/drivers/clk/clk-si514.c
new file mode 100644
index 000000000000..6af7dce54241
--- /dev/null
+++ b/drivers/clk/clk-si514.c
@@ -0,0 +1,379 @@
+/*
+ * 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");