[v2] clk: Add driver for the si544 clock generator chip

diff --git a/Documentation/devicetree/bindings/clock/silabs,si544.txt b/Documentation/devicetree/bindings/clock/silabs,si544.txt
new file mode 100644
index 0000000..eec1787
--- /dev/null
+++ b/Documentation/devicetree/bindings/clock/silabs,si544.txt
@@ -0,0 +1,25 @@ 
+Binding for Silicon Labs 544 programmable I2C clock generator.
+
+Reference
+This binding uses the common clock binding[1]. Details about the device can be
+found in the datasheet[2].
+
+[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
+[2] Si544 datasheet
+    https://www.silabs.com/documents/public/data-sheets/si544-datasheet.pdf
+
+Required properties:
+ - compatible: One of "silabs,si514a", "silabs,si514b" "silabs,si514c" according
+               to the speed grade of the chip.
+ - reg: I2C device address.
+ - #clock-cells: From common clock bindings: Shall be 0.
+
+Optional properties:
+ - clock-output-names: From common clock bindings. Recommended to be "si544".
+
+Example:
+	si544: clock-generator@55 {
+		reg = <0x55>;
+		#clock-cells = <0>;
+		compatible = "silabs,si544b";
+	};
diff --git a/drivers/clk/Kconfig b/drivers/clk/Kconfig
index 98ce9fc..5c7dc8e 100644
--- a/drivers/clk/Kconfig
+++ b/drivers/clk/Kconfig
@@ -91,6 +91,16 @@  config COMMON_CLK_SI514
 	  This driver supports the Silicon Labs 514 programmable clock
 	  generator.
 
+config COMMON_CLK_SI544
+	tristate "Clock driver for SiLabs 544 devices"
+	depends on I2C
+	depends on OF
+	select REGMAP_I2C
+	help
+	---help---
+	  This driver supports the Silicon Labs 544 programmable clock
+	  generator.
+
 config COMMON_CLK_SI570
 	tristate "Clock driver for SiLabs 570 and compatible devices"
 	depends on I2C
diff --git a/drivers/clk/Makefile b/drivers/clk/Makefile
index 71ec41e..bde614a 100644
--- a/drivers/clk/Makefile
+++ b/drivers/clk/Makefile
@@ -44,6 +44,7 @@  obj-$(CONFIG_COMMON_CLK_S2MPS11)	+= clk-s2mps11.o
 obj-$(CONFIG_COMMON_CLK_SCPI)           += clk-scpi.o
 obj-$(CONFIG_COMMON_CLK_SI5351)		+= clk-si5351.o
 obj-$(CONFIG_COMMON_CLK_SI514)		+= clk-si514.o
+obj-$(CONFIG_COMMON_CLK_SI544)		+= clk-si544.o
 obj-$(CONFIG_COMMON_CLK_SI570)		+= clk-si570.o
 obj-$(CONFIG_ARCH_STM32)		+= clk-stm32f4.o
 obj-$(CONFIG_ARCH_STM32)		+= clk-stm32h7.o
diff --git a/drivers/clk/clk-si544.c b/drivers/clk/clk-si544.c
new file mode 100644
index 0000000..a392acf
--- /dev/null
+++ b/drivers/clk/clk-si544.c
@@ -0,0 +1,422 @@ 
+/*
+ * Driver for Silicon Labs Si544 Programmable Oscillator
+ *
+ * Copyright (C) 2018 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 (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
+
+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)
+
+/* Multiplier/divider settings */
+struct clk_si544_muldiv {
+	u32 fb_div_frac;  /* Integer part of feedback divider (32 bits) */
+	u16 fb_div_int;  /* Fractional part of feedback divider (11 bits) */
+	u16 hs_div; /* 1st divider, 5..2046, must be even when >33 */
+	u8 ls_div_bits; /* 2nd divider, as 2^x, range 0..5 */
+};
+
+/* 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;
+
+	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;
+	default:
+		return false;
+	}
+
+	if (frequency > max_freq)
+		return false;
+
+	return true;
+}
+
+/* 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 >= (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 (((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 while preventing overflow */
+	vco = (u64)settings->fb_div_int * FXO;
+	vco += (((u64)settings->fb_div_frac * FXO) + (FXO / 2)) >> 32;
+
+	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) {
+		dev_err(&data->i2c_client->dev, "unable to retrieve settings\n");
+		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 (!rate)
+		return 0;
+
+	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)) {
+		dev_err(&client->dev, "failed to allocate register map\n");
+		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 = 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 si544_remove(struct i2c_client *client)
+{
+	of_clk_del_provider(client->dev.of_node);
+	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,
+	.remove		= si544_remove,
+	.id_table	= si544_id,
+};
+module_i2c_driver(si544_driver);
+
+MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
+MODULE_DESCRIPTION("Si544 driver");
+MODULE_LICENSE("GPL");