drivers/clk/clk-si5341.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Driver for Silicon Labs Si5341/Si5340 Clock generator
 * Copyright (C) 2019 Topic Embedded Products
 * Author: Mike Looijmans <mike.looijmans@topic.nl>
 */

#include <linux/clk.h>
#include <linux/clk-provider.h>
#include <linux/delay.h>
#include <linux/gcd.h>
#include <linux/math64.h>
#include <linux/i2c.h>
#include <linux/module.h>
#include <linux/regmap.h>
#include <linux/slab.h>
#include <asm/unaligned.h>

#define SI5341_MAX_NUM_OUTPUTS 10
#define SI5340_MAX_NUM_OUTPUTS 4

#define SI5341_NUM_SYNTH 5
#define SI5340_NUM_SYNTH 4

/* Range of the synthesizer fractional divider */
#define SI5341_SYNTH_N_MIN	10
#define SI5341_SYNTH_N_MAX	4095

/* The chip can get its input clock from 3 input pins or an XTAL */

/* There is one PLL running at 13500–14256 MHz */
#define SI5341_PLL_VCO_MIN 13500000000ull
#define SI5341_PLL_VCO_MAX 14256000000ull

/* The 5 frequency synthesizers obtain their input from the PLL */
struct clk_si5341_synth {
	struct clk_hw hw;
	struct clk_si5341 *data;
	u8 index;
};
#define to_clk_si5341_synth(_hw) \
	container_of(_hw, struct clk_si5341_synth, hw)

/* The output stages can be connected to any synth (full mux) */
struct clk_si5341_output {
	struct clk_hw hw;
	struct clk_si5341 *data;
	u8 index;
};
#define to_clk_si5341_output(_hw) \
	container_of(_hw, struct clk_si5341_output, hw)

struct clk_si5341 {
	struct clk_hw hw;
	struct regmap *regmap;
	struct i2c_client *i2c_client;
	struct clk_si5341_synth synth[SI5341_NUM_SYNTH];
	struct clk_si5341_output clk[SI5341_MAX_NUM_OUTPUTS];
	struct clk *pxtal;
	const char *pxtal_name;
	const u16 *reg_output_offset;
	const u16 *reg_rdiv_offset;
	u64 freq_vco; /* 13500–14256 MHz */
	u8 num_outputs;
	u8 num_synth;
};
#define to_clk_si5341(_hw)	container_of(_hw, struct clk_si5341, hw)

struct clk_si5341_output_config {
	u8 out_format_drv_bits;
	u8 out_cm_ampl_bits;
	bool synth_master;
	bool always_on;
};

#define SI5341_PAGE		0x0001
#define SI5341_PN_BASE		0x0002
#define SI5341_DEVICE_REV	0x0005
#define SI5341_STATUS		0x000C
#define SI5341_SOFT_RST		0x001C

/* Input dividers (48-bit) */
#define SI5341_IN_PDIV(x)	(0x0208 + ((x) * 10))
#define SI5341_IN_PSET(x)	(0x020E + ((x) * 10))

/* PLL configuration */
#define SI5341_PLL_M_NUM	0x0235
#define SI5341_PLL_M_DEN	0x023B

/* Output configuration */
#define SI5341_OUT_CONFIG(output)	\
			((output)->data->reg_output_offset[(output)->index])
#define SI5341_OUT_FORMAT(output)	(SI5341_OUT_CONFIG(output) + 1)
#define SI5341_OUT_CM(output)		(SI5341_OUT_CONFIG(output) + 2)
#define SI5341_OUT_MUX_SEL(output)	(SI5341_OUT_CONFIG(output) + 3)
#define SI5341_OUT_R_REG(output)	\
			((output)->data->reg_rdiv_offset[(output)->index])

/* Synthesize N divider */
#define SI5341_SYNTH_N_NUM(x)	(0x0302 + ((x) * 11))
#define SI5341_SYNTH_N_DEN(x)	(0x0308 + ((x) * 11))
#define SI5341_SYNTH_N_UPD(x)	(0x030C + ((x) * 11))

/* Synthesizer output enable, phase bypass, power mode */
#define SI5341_SYNTH_N_CLK_TO_OUTX_EN	0x0A03
#define SI5341_SYNTH_N_PIBYP		0x0A04
#define SI5341_SYNTH_N_PDNB		0x0A05
#define SI5341_SYNTH_N_CLK_DIS		0x0B4A

#define SI5341_REGISTER_MAX	0xBFF

/* SI5341_OUT_CONFIG bits */
#define SI5341_OUT_CFG_PDN		BIT(0)
#define SI5341_OUT_CFG_OE		BIT(1)
#define SI5341_OUT_CFG_RDIV_FORCE2	BIT(2)

/* Static configuration (to be moved to firmware) */
struct si5341_reg_default {
	u16 address;
	u8 value;
};

/* Output configuration registers 0..9 are not quite logically organized */
static const u16 si5341_reg_output_offset[] = {
	0x0108,
	0x010D,
	0x0112,
	0x0117,
	0x011C,
	0x0121,
	0x0126,
	0x012B,
	0x0130,
	0x013A,
};

static const u16 si5340_reg_output_offset[] = {
	0x0112,
	0x0117,
	0x0126,
	0x012B,
};

/* The location of the R divider registers */
static const u16 si5341_reg_rdiv_offset[] = {
	0x024A,
	0x024D,
	0x0250,
	0x0253,
	0x0256,
	0x0259,
	0x025C,
	0x025F,
	0x0262,
	0x0268,
};
static const u16 si5340_reg_rdiv_offset[] = {
	0x0250,
	0x0253,
	0x025C,
	0x025F,
};

/*
 * Programming sequence from ClockBuilder, settings to initialize the system
 * using only the XTAL input, without pre-divider.
 * This also contains settings that aren't mentioned anywhere in the datasheet.
 * The "known" settings like synth and output configuration are done later.
 */
static const struct si5341_reg_default si5341_reg_defaults[] = {
	{ 0x0017, 0x3A }, /* INT mask (disable interrupts) */
	{ 0x0018, 0xFF }, /* INT mask */
	{ 0x0021, 0x0F }, /* Select XTAL as input */
	{ 0x0022, 0x00 }, /* Not in datasheet */
	{ 0x002B, 0x02 }, /* SPI config */
	{ 0x002C, 0x20 }, /* LOS enable for XTAL */
	{ 0x002D, 0x00 }, /* LOS timing */
	{ 0x002E, 0x00 },
	{ 0x002F, 0x00 },
	{ 0x0030, 0x00 },
	{ 0x0031, 0x00 },
	{ 0x0032, 0x00 },
	{ 0x0033, 0x00 },
	{ 0x0034, 0x00 },
	{ 0x0035, 0x00 },
	{ 0x0036, 0x00 },
	{ 0x0037, 0x00 },
	{ 0x0038, 0x00 }, /* LOS setting (thresholds) */
	{ 0x0039, 0x00 },
	{ 0x003A, 0x00 },
	{ 0x003B, 0x00 },
	{ 0x003C, 0x00 },
	{ 0x003D, 0x00 }, /* LOS setting (thresholds) end */
	{ 0x0041, 0x00 }, /* LOS0_DIV_SEL */
	{ 0x0042, 0x00 }, /* LOS1_DIV_SEL */
	{ 0x0043, 0x00 }, /* LOS2_DIV_SEL */
	{ 0x0044, 0x00 }, /* LOS3_DIV_SEL */
	{ 0x009E, 0x00 }, /* Not in datasheet */
	{ 0x0102, 0x01 }, /* Enable outputs */
	{ 0x013F, 0x00 }, /* Not in datasheet */
	{ 0x0140, 0x00 }, /* Not in datasheet */
	{ 0x0141, 0x40 }, /* OUT LOS */
	{ 0x0202, 0x00 }, /* XAXB_FREQ_OFFSET (=0)*/
	{ 0x0203, 0x00 },
	{ 0x0204, 0x00 },
	{ 0x0205, 0x00 },
	{ 0x0206, 0x00 }, /* PXAXB (2^x) */
	{ 0x0208, 0x00 }, /* Px divider setting (usually 0) */
	{ 0x0209, 0x00 },
	{ 0x020A, 0x00 },
	{ 0x020B, 0x00 },
	{ 0x020C, 0x00 },
	{ 0x020D, 0x00 },
	{ 0x020E, 0x00 },
	{ 0x020F, 0x00 },
	{ 0x0210, 0x00 },
	{ 0x0211, 0x00 },
	{ 0x0212, 0x00 },
	{ 0x0213, 0x00 },
	{ 0x0214, 0x00 },
	{ 0x0215, 0x00 },
	{ 0x0216, 0x00 },
	{ 0x0217, 0x00 },
	{ 0x0218, 0x00 },
	{ 0x0219, 0x00 },
	{ 0x021A, 0x00 },
	{ 0x021B, 0x00 },
	{ 0x021C, 0x00 },
	{ 0x021D, 0x00 },
	{ 0x021E, 0x00 },
	{ 0x021F, 0x00 },
	{ 0x0220, 0x00 },
	{ 0x0221, 0x00 },
	{ 0x0222, 0x00 },
	{ 0x0223, 0x00 },
	{ 0x0224, 0x00 },
	{ 0x0225, 0x00 },
	{ 0x0226, 0x00 },
	{ 0x0227, 0x00 },
	{ 0x0228, 0x00 },
	{ 0x0229, 0x00 },
	{ 0x022A, 0x00 },
	{ 0x022B, 0x00 },
	{ 0x022C, 0x00 },
	{ 0x022D, 0x00 },
	{ 0x022E, 0x00 },
	{ 0x022F, 0x00 }, /* Px divider setting (usually 0) end */
	{ 0x026B, 0x00 }, /* DESIGN_ID (ASCII string) */
	{ 0x026C, 0x00 },
	{ 0x026D, 0x00 },
	{ 0x026E, 0x00 },
	{ 0x026F, 0x00 },
	{ 0x0270, 0x00 },
	{ 0x0271, 0x00 },
	{ 0x0272, 0x00 }, /* DESIGN_ID (ASCII string) end */
	{ 0x0339, 0x1F }, /* N_FSTEP_MSK */
	{ 0x033B, 0x00 }, /* Nx_FSTEPW (Frequency step) */
	{ 0x033C, 0x00 },
	{ 0x033D, 0x00 },
	{ 0x033E, 0x00 },
	{ 0x033F, 0x00 },
	{ 0x0340, 0x00 },
	{ 0x0341, 0x00 },
	{ 0x0342, 0x00 },
	{ 0x0343, 0x00 },
	{ 0x0344, 0x00 },
	{ 0x0345, 0x00 },
	{ 0x0346, 0x00 },
	{ 0x0347, 0x00 },
	{ 0x0348, 0x00 },
	{ 0x0349, 0x00 },
	{ 0x034A, 0x00 },
	{ 0x034B, 0x00 },
	{ 0x034C, 0x00 },
	{ 0x034D, 0x00 },
	{ 0x034E, 0x00 },
	{ 0x034F, 0x00 },
	{ 0x0350, 0x00 },
	{ 0x0351, 0x00 },
	{ 0x0352, 0x00 },
	{ 0x0353, 0x00 },
	{ 0x0354, 0x00 },
	{ 0x0355, 0x00 },
	{ 0x0356, 0x00 },
	{ 0x0357, 0x00 },
	{ 0x0358, 0x00 }, /* Nx_FSTEPW (Frequency step) end */
	{ 0x0359, 0x00 }, /* Nx_DELAY */
	{ 0x035A, 0x00 },
	{ 0x035B, 0x00 },
	{ 0x035C, 0x00 },
	{ 0x035D, 0x00 },
	{ 0x035E, 0x00 },
	{ 0x035F, 0x00 },
	{ 0x0360, 0x00 },
	{ 0x0361, 0x00 },
	{ 0x0362, 0x00 }, /* Nx_DELAY end */
	{ 0x0802, 0x00 }, /* Not in datasheet */
	{ 0x0803, 0x00 }, /* Not in datasheet */
	{ 0x0804, 0x00 }, /* Not in datasheet */
	{ 0x090E, 0x02 }, /* XAXB_EXTCLK_EN=0 XAXB_PDNB=1 (use XTAL) */
	{ 0x091C, 0x04 }, /* ZDM_EN=4 (Normal mode) */
	{ 0x0943, 0x00 }, /* IO_VDD_SEL=0 (0=1v8, use 1=3v3) */
	{ 0x0949, 0x00 }, /* IN_EN (disable input clocks) */
	{ 0x094A, 0x00 }, /* INx_TO_PFD_EN (disabled) */
	{ 0x0A02, 0x00 }, /* Not in datasheet */
	{ 0x0B44, 0x0F }, /* PDIV_ENB (datasheet does not mention what it is) */
};

/* Read and interpret a 44-bit followed by a 32-bit value in the regmap */
static int si5341_decode_44_32(struct regmap *regmap, unsigned int reg,
	u64 *val1, u32 *val2)
{
	int err;
	u8 r[10];

	err = regmap_bulk_read(regmap, reg, r, 10);
	if (err < 0)
		return err;

	*val1 = ((u64)((r[5] & 0x0f) << 8 | r[4]) << 32) |
		 (get_unaligned_le32(r));
	*val2 = get_unaligned_le32(&r[6]);

	return 0;
}

static int si5341_encode_44_32(struct regmap *regmap, unsigned int reg,
	u64 n_num, u32 n_den)
{
	u8 r[10];

	/* Shift left as far as possible without overflowing */
	while (!(n_num & BIT_ULL(43)) && !(n_den & BIT(31))) {
		n_num <<= 1;
		n_den <<= 1;
	}

	/* 44 bits (6 bytes) numerator */
	put_unaligned_le32(n_num, r);
	r[4] = (n_num >> 32) & 0xff;
	r[5] = (n_num >> 40) & 0x0f;
	/* 32 bits denominator */
	put_unaligned_le32(n_den, &r[6]);

	/* Program the fraction */
	return regmap_bulk_write(regmap, reg, r, sizeof(r));
}

/* VCO, we assume it runs at a constant frequency */
static unsigned long si5341_clk_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	struct clk_si5341 *data = to_clk_si5341(hw);
	int err;
	u64 res;
	u64 m_num;
	u32 m_den;
	unsigned int shift;

	/* Assume that PDIV is not being used, just read the PLL setting */
	err = si5341_decode_44_32(data->regmap, SI5341_PLL_M_NUM,
				&m_num, &m_den);
	if (err < 0)
		return 0;

	if (!m_num || !m_den)
		return 0;

	/*
	 * Though m_num is 64-bit, only the upper bits are actually used. While
	 * calculating m_num and m_den, they are shifted as far as possible to
	 * the left. To avoid 96-bit division here, we just shift them back so
	 * we can do with just 64 bits.
	 */
	shift = 0;
	res = m_num;
	while (res & 0xffff00000000ULL) {
		++shift;
		res >>= 1;
	}
	res *= parent_rate;
	do_div(res, (m_den >> shift));

	/* We cannot return the actual frequency in 32 bit, store it locally */
	data->freq_vco = res;

	/* Report kHz since the value is out of range */
	do_div(res, 1000);

	return (unsigned long)res;
}

static const struct clk_ops si5341_clk_ops = {
	.recalc_rate = si5341_clk_recalc_rate,
};

/* Synthesizers, there are 5 synthesizers that connect to any of the outputs */

/* The synthesizer is on if all power and enable bits are set */
static int si5341_synth_clk_is_on(struct clk_hw *hw)
{
	struct clk_si5341_synth *synth = to_clk_si5341_synth(hw);
	int err;
	u32 val;
	u8 index = synth->index;

	err = regmap_read(synth->data->regmap,
			SI5341_SYNTH_N_CLK_TO_OUTX_EN, &val);
	if (err < 0)
		return 0;

	if (!(val & BIT(index)))
		return 0;

	err = regmap_read(synth->data->regmap, SI5341_SYNTH_N_PDNB, &val);
	if (err < 0)
		return 0;

	if (!(val & BIT(index)))
		return 0;

	/* This bit must be 0 for the synthesizer to receive clock input */
	err = regmap_read(synth->data->regmap, SI5341_SYNTH_N_CLK_DIS, &val);
	if (err < 0)
		return 0;

	return !(val & BIT(index));
}

static void si5341_synth_clk_unprepare(struct clk_hw *hw)
{
	struct clk_si5341_synth *synth = to_clk_si5341_synth(hw);
	u8 index = synth->index; /* In range 0..5 */
	u8 mask = BIT(index);

	/* Disable output */
	regmap_update_bits(synth->data->regmap,
		SI5341_SYNTH_N_CLK_TO_OUTX_EN, mask, 0);
	/* Power down */
	regmap_update_bits(synth->data->regmap,
		SI5341_SYNTH_N_PDNB, mask, 0);
	/* Disable clock input to synth (set to 1 to disable) */
	regmap_update_bits(synth->data->regmap,
		SI5341_SYNTH_N_CLK_DIS, mask, mask);
}

static int si5341_synth_clk_prepare(struct clk_hw *hw)
{
	struct clk_si5341_synth *synth = to_clk_si5341_synth(hw);
	int err;
	u8 index = synth->index;
	u8 mask = BIT(index);

	/* Power up */
	err = regmap_update_bits(synth->data->regmap,
		SI5341_SYNTH_N_PDNB, mask, mask);
	if (err < 0)
		return err;

	/* Enable clock input to synth (set bit to 0 to enable) */
	err = regmap_update_bits(synth->data->regmap,
		SI5341_SYNTH_N_CLK_DIS, mask, 0);
	if (err < 0)
		return err;

	/* Enable output */
	return regmap_update_bits(synth->data->regmap,
		SI5341_SYNTH_N_CLK_TO_OUTX_EN, mask, mask);
}

/* Synth clock frequency: Fvco * n_den / n_den, with Fvco in 13500-14256 MHz */
static unsigned long si5341_synth_clk_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	struct clk_si5341_synth *synth = to_clk_si5341_synth(hw);
	u64 f;
	u64 n_num;
	u32 n_den;
	int err;

	err = si5341_decode_44_32(synth->data->regmap,
			SI5341_SYNTH_N_NUM(synth->index), &n_num, &n_den);
	if (err < 0)
		return err;

	/*
	 * n_num and n_den are shifted left as much as possible, so to prevent
	 * overflow in 64-bit math, we shift n_den 4 bits to the right
	 */
	f = synth->data->freq_vco;
	f *= n_den >> 4;

	/* Now we need to to 64-bit division: f/n_num */
	/* And compensate for the 4 bits we dropped */
	f = div64_u64(f, (n_num >> 4));

	return f;
}

static long si5341_synth_clk_round_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long *parent_rate)
{
	struct clk_si5341_synth *synth = to_clk_si5341_synth(hw);
	u64 f;

	/* The synthesizer accuracy is such that anything in range will work */
	f = synth->data->freq_vco;
	do_div(f, SI5341_SYNTH_N_MAX);
	if (rate < f)
		return f;

	f = synth->data->freq_vco;
	do_div(f, SI5341_SYNTH_N_MIN);
	if (rate > f)
		return f;

	return rate;
}

static int si5341_synth_program(struct clk_si5341_synth *synth,
	u64 n_num, u32 n_den, bool is_integer)
{
	int err;
	u8 index = synth->index;

	err = si5341_encode_44_32(synth->data->regmap,
			SI5341_SYNTH_N_NUM(index), n_num, n_den);

	err = regmap_update_bits(synth->data->regmap,
		SI5341_SYNTH_N_PIBYP, BIT(index), is_integer ? BIT(index) : 0);
	if (err < 0)
		return err;

	return regmap_write(synth->data->regmap,
		SI5341_SYNTH_N_UPD(index), 0x01);
}


static int si5341_synth_clk_set_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long parent_rate)
{
	struct clk_si5341_synth *synth = to_clk_si5341_synth(hw);
	u64 n_num;
	u32 n_den;
	u32 r;
	u32 g;
	bool is_integer;

	n_num = synth->data->freq_vco;
	n_den = rate;

	/* see if there's an integer solution */
	r = do_div(n_num, rate);
	is_integer = (r == 0);
	if (is_integer) {
		/* Integer divider equal to n_num */
		n_den = 1;
	} else {
		/* Calculate a fractional solution */
		g = gcd(r, rate);
		n_den = rate / g;
		n_num *= n_den;
		n_num += r / g;
	}

	dev_dbg(&synth->data->i2c_client->dev,
			"%s(%u): n=0x%llx d=0x%x %s\n", __func__,
				synth->index, n_num, n_den,
				is_integer ? "int" : "frac");

	return si5341_synth_program(synth, n_num, n_den, is_integer);
}

static const struct clk_ops si5341_synth_clk_ops = {
	.is_prepared = si5341_synth_clk_is_on,
	.prepare = si5341_synth_clk_prepare,
	.unprepare = si5341_synth_clk_unprepare,
	.recalc_rate = si5341_synth_clk_recalc_rate,
	.round_rate = si5341_synth_clk_round_rate,
	.set_rate = si5341_synth_clk_set_rate,
};

static int si5341_output_clk_is_on(struct clk_hw *hw)
{
	struct clk_si5341_output *output = to_clk_si5341_output(hw);
	int err;
	u32 val;

	err = regmap_read(output->data->regmap,
			SI5341_OUT_CONFIG(output), &val);
	if (err < 0)
		return err;

	/* Bit 0=PDN, 1=OE so only a value of 0x2 enables the output */
	return (val & 0x03) == SI5341_OUT_CFG_OE;
}

/* Disables and then powers down the output */
static void si5341_output_clk_unprepare(struct clk_hw *hw)
{
	struct clk_si5341_output *output = to_clk_si5341_output(hw);

	regmap_update_bits(output->data->regmap,
			SI5341_OUT_CONFIG(output),
			SI5341_OUT_CFG_OE, 0);
	regmap_update_bits(output->data->regmap,
			SI5341_OUT_CONFIG(output),
			SI5341_OUT_CFG_PDN, SI5341_OUT_CFG_PDN);
}

/* Powers up and then enables the output */
static int si5341_output_clk_prepare(struct clk_hw *hw)
{
	struct clk_si5341_output *output = to_clk_si5341_output(hw);
	int err;

	err = regmap_update_bits(output->data->regmap,
			SI5341_OUT_CONFIG(output),
			SI5341_OUT_CFG_PDN, 0);
	if (err < 0)
		return err;

	return regmap_update_bits(output->data->regmap,
			SI5341_OUT_CONFIG(output),
			SI5341_OUT_CFG_OE, SI5341_OUT_CFG_OE);
}

static unsigned long si5341_output_clk_recalc_rate(struct clk_hw *hw,
		unsigned long parent_rate)
{
	struct clk_si5341_output *output = to_clk_si5341_output(hw);
	int err;
	u32 val;
	u32 r_divider;
	u8 r[3];

	err = regmap_bulk_read(output->data->regmap,
			SI5341_OUT_R_REG(output), r, 3);
	if (err < 0)
		return err;

	/* Calculate value as 24-bit integer*/
	r_divider = r[2] << 16 | r[1] << 8 | r[0];

	/* If Rx_REG is zero, the divider is disabled, so return a "0" rate */
	if (!r_divider)
		return 0;

	/* Divider is 2*(Rx_REG+1) */
	r_divider += 1;
	r_divider <<= 1;

	err = regmap_read(output->data->regmap,
			SI5341_OUT_CONFIG(output), &val);
	if (err < 0)
		return err;

	if (val & SI5341_OUT_CFG_RDIV_FORCE2)
		r_divider = 2;

	return parent_rate / r_divider;
}

static long si5341_output_clk_round_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long *parent_rate)
{
	unsigned long r;

	r = *parent_rate >> 1;

	/* If rate is an even divisor, no changes to parent required */
	if (r && !(r % rate))
		return (long)rate;

	if (clk_hw_get_flags(hw) & CLK_SET_RATE_PARENT) {
		if (rate > 200000000) {
			/* minimum r-divider is 2 */
			r = 2;
		} else {
			/* Take a parent frequency near 400 MHz */
			r = (400000000u / rate) & ~1;
		}
		*parent_rate = r * rate;
	} else {
		/* We cannot change our parent's rate, report what we can do */
		r /= rate;
		rate = *parent_rate / (r << 1);
	}

	return rate;
}

static int si5341_output_clk_set_rate(struct clk_hw *hw, unsigned long rate,
		unsigned long parent_rate)
{
	struct clk_si5341_output *output = to_clk_si5341_output(hw);
	/* Frequency divider is (r_div + 1) * 2 */
	u32 r_div = (parent_rate / rate) >> 1;
	int err;
	u8 r[3];

	if (r_div <= 1)
		r_div = 0;
	else if (r_div >= BIT(24))
		r_div = BIT(24) - 1;
	else
		--r_div;

	/* For a value of "2", we set the "OUT0_RDIV_FORCE2" bit */
	err = regmap_update_bits(output->data->regmap,
			SI5341_OUT_CONFIG(output),
			SI5341_OUT_CFG_RDIV_FORCE2,
			(r_div == 0) ? SI5341_OUT_CFG_RDIV_FORCE2 : 0);
	if (err < 0)
		return err;

	/* Always write Rx_REG, because a zero value disables the divider */
	r[0] = r_div ? (r_div & 0xff) : 1;
	r[1] = (r_div >> 8) & 0xff;
	r[2] = (r_div >> 16) & 0xff;
	err = regmap_bulk_write(output->data->regmap,
			SI5341_OUT_R_REG(output), r, 3);

	return 0;
}

static int si5341_output_reparent(struct clk_si5341_output *output, u8 index)
{
	return regmap_update_bits(output->data->regmap,
		SI5341_OUT_MUX_SEL(output), 0x07, index);
}

static int si5341_output_set_parent(struct clk_hw *hw, u8 index)
{
	struct clk_si5341_output *output = to_clk_si5341_output(hw);

	if (index >= output->data->num_synth)
		return -EINVAL;

	return si5341_output_reparent(output, index);
}

static u8 si5341_output_get_parent(struct clk_hw *hw)
{
	struct clk_si5341_output *output = to_clk_si5341_output(hw);
	int err;
	u32 val;

	err = regmap_read(output->data->regmap,
			SI5341_OUT_MUX_SEL(output), &val);

	return val & 0x7;
}

static const struct clk_ops si5341_output_clk_ops = {
	.is_prepared = si5341_output_clk_is_on,
	.prepare = si5341_output_clk_prepare,
	.unprepare = si5341_output_clk_unprepare,
	.recalc_rate = si5341_output_clk_recalc_rate,
	.round_rate = si5341_output_clk_round_rate,
	.set_rate = si5341_output_clk_set_rate,
	.set_parent = si5341_output_set_parent,
	.get_parent = si5341_output_get_parent,
};

/*
 * The chip can be bought in a pre-programmed version, or one can program the
 * NVM in the chip to boot up in a preset mode. This routine tries to determine
 * if that's the case, or if we need to reset and program everything from
 * scratch. Returns negative error, or true/false.
 */
static int si5341_is_programmed_already(struct clk_si5341 *data)
{
	int err;
	u8 r[4];

	/* Read the PLL divider value, it must have a non-zero value */
	err = regmap_bulk_read(data->regmap, SI5341_PLL_M_DEN,
			r, ARRAY_SIZE(r));
	if (err < 0)
		return err;

	return !!get_unaligned_le32(r);
}

static struct clk_hw *
of_clk_si5341_get(struct of_phandle_args *clkspec, void *_data)
{
	struct clk_si5341 *data = _data;
	unsigned int idx = clkspec->args[1];
	unsigned int group = clkspec->args[0];

	switch (group) {
	case 0:
		if (idx >= data->num_outputs) {
			dev_err(&data->i2c_client->dev,
				"invalid output index %u\n", idx);
			return ERR_PTR(-EINVAL);
		}
		return &data->clk[idx].hw;
	case 1:
		if (idx >= data->num_synth) {
			dev_err(&data->i2c_client->dev,
				"invalid synthesizer index %u\n", idx);
			return ERR_PTR(-EINVAL);
		}
		return &data->synth[idx].hw;
	case 2:
		if (idx > 0) {
			dev_err(&data->i2c_client->dev,
				"invalid PLL index %u\n", idx);
			return ERR_PTR(-EINVAL);
		}
		return &data->hw;
	default:
		dev_err(&data->i2c_client->dev, "invalid group %u\n", group);
		return ERR_PTR(-EINVAL);
	}
}

static int si5341_probe_chip_id(struct clk_si5341 *data)
{
	int err;
	u8 reg[4];
	u16 model;

	err = regmap_bulk_read(data->regmap, SI5341_PN_BASE, reg,
				ARRAY_SIZE(reg));
	if (err < 0) {
		dev_err(&data->i2c_client->dev, "Failed to read chip ID\n");
		return err;
	}

	model = get_unaligned_le16(reg);

	dev_info(&data->i2c_client->dev, "Chip: %x Grade: %u Rev: %u\n",
		 model, reg[2], reg[3]);

	switch (model) {
	case 0x5340:
		data->num_outputs = SI5340_MAX_NUM_OUTPUTS;
		data->num_synth = SI5340_NUM_SYNTH;
		data->reg_output_offset = si5340_reg_output_offset;
		data->reg_rdiv_offset = si5340_reg_rdiv_offset;
		break;
	case 0x5341:
		data->num_outputs = SI5341_MAX_NUM_OUTPUTS;
		data->num_synth = SI5341_NUM_SYNTH;
		data->reg_output_offset = si5341_reg_output_offset;
		data->reg_rdiv_offset = si5341_reg_rdiv_offset;
		break;
	default:
		dev_err(&data->i2c_client->dev, "Model '%x' not supported\n",
			model);
		return -EINVAL;
	}

	return 0;
}

/* Read active settings into the regmap cache for later reference */
static int si5341_read_settings(struct clk_si5341 *data)
{
	int err;
	u8 i;
	u8 r[10];

	err = regmap_bulk_read(data->regmap, SI5341_PLL_M_NUM, r, 10);
	if (err < 0)
		return err;

	err = regmap_bulk_read(data->regmap,
				SI5341_SYNTH_N_CLK_TO_OUTX_EN, r, 3);
	if (err < 0)
		return err;

	err = regmap_bulk_read(data->regmap,
				SI5341_SYNTH_N_CLK_DIS, r, 1);
	if (err < 0)
		return err;

	for (i = 0; i < data->num_synth; ++i) {
		err = regmap_bulk_read(data->regmap,
					SI5341_SYNTH_N_NUM(i), r, 10);
		if (err < 0)
			return err;
	}

	for (i = 0; i < data->num_outputs; ++i) {
		err = regmap_bulk_read(data->regmap,
					data->reg_output_offset[i], r, 4);
		if (err < 0)
			return err;

		err = regmap_bulk_read(data->regmap,
					data->reg_rdiv_offset[i], r, 3);
		if (err < 0)
			return err;
	}

	return 0;
}

static int si5341_write_multiple(struct clk_si5341 *data,
	const struct si5341_reg_default *values, unsigned int num_values)
{
	unsigned int i;
	int res;

	for (i = 0; i < num_values; ++i) {
		res = regmap_write(data->regmap,
			values[i].address, values[i].value);
		if (res < 0) {
			dev_err(&data->i2c_client->dev,
				"Failed to write %#x:%#x\n",
				values[i].address, values[i].value);
			return res;
		}
	}

	return 0;
}

static const struct si5341_reg_default si5341_preamble[] = {
	{ 0x0B25, 0x00 },
	{ 0x0502, 0x01 },
	{ 0x0505, 0x03 },
	{ 0x0957, 0x1F },
	{ 0x0B4E, 0x1A },
};

static int si5341_send_preamble(struct clk_si5341 *data)
{
	int res;
	u32 revision;

	/* For revision 2 and up, the values are slightly different */
	res = regmap_read(data->regmap, SI5341_DEVICE_REV, &revision);
	if (res < 0)
		return res;

	/* Write "preamble" as specified by datasheet */
	res = regmap_write(data->regmap, 0xB24, revision < 2 ? 0xD8 : 0xC0);
	if (res < 0)
		return res;
	res = si5341_write_multiple(data,
		si5341_preamble, ARRAY_SIZE(si5341_preamble));
	if (res < 0)
		return res;

	/* Datasheet specifies a 300ms wait after sending the preamble */
	msleep(300);

	return 0;
}

/* Perform a soft reset and write post-amble */
static int si5341_finalize_defaults(struct clk_si5341 *data)
{
	int res;
	u32 revision;

	res = regmap_read(data->regmap, SI5341_DEVICE_REV, &revision);
	if (res < 0)
		return res;

	dev_dbg(&data->i2c_client->dev, "%s rev=%u\n", __func__, revision);

	res = regmap_write(data->regmap, SI5341_SOFT_RST, 0x01);
	if (res < 0)
		return res;

	/* Datasheet does not explain these nameless registers */
	res = regmap_write(data->regmap, 0xB24, revision < 2 ? 0xDB : 0xC3);
	if (res < 0)
		return res;
	res = regmap_write(data->regmap, 0x0B25, 0x02);
	if (res < 0)
		return res;

	return 0;
}


static const struct regmap_range si5341_regmap_volatile_range[] = {
	regmap_reg_range(0x000C, 0x0012), /* Status */
	regmap_reg_range(0x001C, 0x001E), /* reset, finc/fdec */
	regmap_reg_range(0x00E2, 0x00FE), /* NVM, interrupts, device ready */
	/* Update bits for synth config */
	regmap_reg_range(SI5341_SYNTH_N_UPD(0), SI5341_SYNTH_N_UPD(0)),
	regmap_reg_range(SI5341_SYNTH_N_UPD(1), SI5341_SYNTH_N_UPD(1)),
	regmap_reg_range(SI5341_SYNTH_N_UPD(2), SI5341_SYNTH_N_UPD(2)),
	regmap_reg_range(SI5341_SYNTH_N_UPD(3), SI5341_SYNTH_N_UPD(3)),
	regmap_reg_range(SI5341_SYNTH_N_UPD(4), SI5341_SYNTH_N_UPD(4)),
};

static const struct regmap_access_table si5341_regmap_volatile = {
	.yes_ranges = si5341_regmap_volatile_range,
	.n_yes_ranges = ARRAY_SIZE(si5341_regmap_volatile_range),
};

/* Pages 0, 1, 2, 3, 9, A, B are valid, so there are 12 pages */
static const struct regmap_range_cfg si5341_regmap_ranges[] = {
	{
		.range_min = 0,
		.range_max = SI5341_REGISTER_MAX,
		.selector_reg = SI5341_PAGE,
		.selector_mask = 0xff,
		.selector_shift = 0,
		.window_start = 0,
		.window_len = 256,
	},
};

static const struct regmap_config si5341_regmap_config = {
	.reg_bits = 8,
	.val_bits = 8,
	.cache_type = REGCACHE_RBTREE,
	.ranges = si5341_regmap_ranges,
	.num_ranges = ARRAY_SIZE(si5341_regmap_ranges),
	.max_register = SI5341_REGISTER_MAX,
	.volatile_table = &si5341_regmap_volatile,
};

static int si5341_dt_parse_dt(struct i2c_client *client,
	struct clk_si5341_output_config *config)
{
	struct device_node *child;
	struct device_node *np = client->dev.of_node;
	u32 num;
	u32 val;

	memset(config, 0, sizeof(struct clk_si5341_output_config) *
				SI5341_MAX_NUM_OUTPUTS);

	for_each_child_of_node(np, child) {
		if (of_property_read_u32(child, "reg", &num)) {
			dev_err(&client->dev, "missing reg property of %s\n",
				child->name);
			goto put_child;
		}

		if (num >= SI5341_MAX_NUM_OUTPUTS) {
			dev_err(&client->dev, "invalid clkout %d\n", num);
			goto put_child;
		}

		if (!of_property_read_u32(child, "silabs,format", &val)) {
			/* Set cm and ampl conservatively to 3v3 settings */
			switch (val) {
			case 1: /* normal differential */
				config[num].out_cm_ampl_bits = 0x33;
				break;
			case 2: /* low-power differential */
				config[num].out_cm_ampl_bits = 0x13;
				break;
			case 4: /* LVCMOS */
				config[num].out_cm_ampl_bits = 0x33;
				/* Set SI recommended impedance for LVCMOS */
				config[num].out_format_drv_bits |= 0xc0;
				break;
			default:
				dev_err(&client->dev,
					"invalid silabs,format %u for %u\n",
					val, num);
				goto put_child;
			}
			config[num].out_format_drv_bits &= ~0x07;
			config[num].out_format_drv_bits |= val & 0x07;
			/* Always enable the SYNC feature */
			config[num].out_format_drv_bits |= 0x08;
		}

		if (!of_property_read_u32(child, "silabs,common-mode", &val)) {
			if (val > 0xf) {
				dev_err(&client->dev,
					"invalid silabs,common-mode %u\n",
					val);
				goto put_child;
			}
			config[num].out_cm_ampl_bits &= 0xf0;
			config[num].out_cm_ampl_bits |= val & 0x0f;
		}

		if (!of_property_read_u32(child, "silabs,amplitude", &val)) {
			if (val > 0xf) {
				dev_err(&client->dev,
					"invalid silabs,amplitude %u\n",
					val);
				goto put_child;
			}
			config[num].out_cm_ampl_bits &= 0x0f;
			config[num].out_cm_ampl_bits |= (val << 4) & 0xf0;
		}

		if (of_property_read_bool(child, "silabs,disable-high"))
			config[num].out_format_drv_bits |= 0x10;

		config[num].synth_master =
			of_property_read_bool(child, "silabs,synth-master");

		config[num].always_on =
			of_property_read_bool(child, "always-on");
	}

	return 0;

put_child:
	of_node_put(child);
	return -EINVAL;
}

/*
 * If not pre-configured, calculate and set the PLL configuration manually.
 * For low-jitter performance, the PLL should be set such that the synthesizers
 * only need integer division.
 * Without any user guidance, we'll set the PLL to 14GHz, which still allows
 * the chip to generate any frequency on its outputs, but jitter performance
 * may be sub-optimal.
 */
static int si5341_initialize_pll(struct clk_si5341 *data)
{
	struct device_node *np = data->i2c_client->dev.of_node;
	u32 m_num = 0;
	u32 m_den = 0;

	if (of_property_read_u32(np, "silabs,pll-m-num", &m_num)) {
		dev_err(&data->i2c_client->dev,
			"PLL configuration requires silabs,pll-m-num\n");
	}
	if (of_property_read_u32(np, "silabs,pll-m-den", &m_den)) {
		dev_err(&data->i2c_client->dev,
			"PLL configuration requires silabs,pll-m-den\n");
	}

	if (!m_num || !m_den) {
		dev_err(&data->i2c_client->dev,
			"PLL configuration invalid, assume 14GHz\n");
		m_den = clk_get_rate(data->pxtal) / 10;
		m_num = 1400000000;
	}

	return si5341_encode_44_32(data->regmap,
			SI5341_PLL_M_NUM, m_num, m_den);
}

static int si5341_probe(struct i2c_client *client,
		const struct i2c_device_id *id)
{
	struct clk_si5341 *data;
	struct clk_init_data init;
	const char *root_clock_name;
	const char *synth_clock_names[SI5341_NUM_SYNTH];
	int err;
	unsigned int i;
	struct clk_si5341_output_config config[SI5341_MAX_NUM_OUTPUTS];
	bool initialization_required;

	data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
	if (!data)
		return -ENOMEM;

	data->i2c_client = client;

	data->pxtal = devm_clk_get(&client->dev, "xtal");
	if (IS_ERR(data->pxtal)) {
		if (PTR_ERR(data->pxtal) == -EPROBE_DEFER)
			return -EPROBE_DEFER;

		dev_err(&client->dev, "Missing xtal clock input\n");
	}

	err = si5341_dt_parse_dt(client, config);
	if (err)
		return err;

	if (of_property_read_string(client->dev.of_node, "clock-output-names",
			&init.name))
		init.name = client->dev.of_node->name;
	root_clock_name = init.name;

	data->regmap = devm_regmap_init_i2c(client, &si5341_regmap_config);
	if (IS_ERR(data->regmap))
		return PTR_ERR(data->regmap);

	i2c_set_clientdata(client, data);

	err = si5341_probe_chip_id(data);
	if (err < 0)
		return err;

	/* "Activate" the xtal (usually a fixed clock) */
	clk_prepare_enable(data->pxtal);

	if (of_property_read_bool(client->dev.of_node, "silabs,reprogram")) {
		initialization_required = true;
	} else {
		err = si5341_is_programmed_already(data);
		if (err < 0)
			return err;

		initialization_required = !err;
	}

	if (initialization_required) {
		/* Populate the regmap cache in preparation for "cache only" */
		err = si5341_read_settings(data);
		if (err < 0)
			return err;

		err = si5341_send_preamble(data);
		if (err < 0)
			return err;

		/*
		 * We intend to send all 'final' register values in a single
		 * transaction. So cache all register writes until we're done
		 * configuring.
		 */
		regcache_cache_only(data->regmap, true);

		/* Write the configuration pairs from the firmware blob */
		err = si5341_write_multiple(data, si5341_reg_defaults,
					ARRAY_SIZE(si5341_reg_defaults));
		if (err < 0)
			return err;

		/* PLL configuration is required */
		err = si5341_initialize_pll(data);
		if (err < 0)
			return err;
	}

	/* Register the PLL */
	data->pxtal_name = __clk_get_name(data->pxtal);
	init.parent_names = &data->pxtal_name;
	init.num_parents = 1; /* For now, only XTAL input supported */
	init.ops = &si5341_clk_ops;
	init.flags = 0;
	data->hw.init = &init;

	err = devm_clk_hw_register(&client->dev, &data->hw);
	if (err) {
		dev_err(&client->dev, "clock registration failed\n");
		return err;
	}

	init.num_parents = 1;
	init.parent_names = &root_clock_name;
	init.ops = &si5341_synth_clk_ops;
	for (i = 0; i < data->num_synth; ++i) {
		synth_clock_names[i] = devm_kasprintf(&client->dev, GFP_KERNEL,
				"%s.N%u", client->dev.of_node->name, i);
		init.name = synth_clock_names[i];
		data->synth[i].index = i;
		data->synth[i].data = data;
		data->synth[i].hw.init = &init;
		err = devm_clk_hw_register(&client->dev, &data->synth[i].hw);
		if (err) {
			dev_err(&client->dev,
				"synth N%u registration failed\n", i);
		}
	}

	init.num_parents = data->num_synth;
	init.parent_names = synth_clock_names;
	init.ops = &si5341_output_clk_ops;
	for (i = 0; i < data->num_outputs; ++i) {
		init.name = kasprintf(GFP_KERNEL, "%s.%d",
			client->dev.of_node->name, i);
		init.flags = config[i].synth_master ? CLK_SET_RATE_PARENT : 0;
		data->clk[i].index = i;
		data->clk[i].data = data;
		data->clk[i].hw.init = &init;
		if (config[i].out_format_drv_bits & 0x07) {
			regmap_write(data->regmap,
				SI5341_OUT_FORMAT(&data->clk[i]),
				config[i].out_format_drv_bits);
			regmap_write(data->regmap,
				SI5341_OUT_CM(&data->clk[i]),
				config[i].out_cm_ampl_bits);
		}
		err = devm_clk_hw_register(&client->dev, &data->clk[i].hw);
		kfree(init.name); /* clock framework made a copy of the name */
		if (err) {
			dev_err(&client->dev,
				"output %u registration failed\n", i);
			return err;
		}
		if (config[i].always_on)
			clk_prepare(data->clk[i].hw.clk);
	}

	err = of_clk_add_hw_provider(client->dev.of_node, of_clk_si5341_get,
			data);
	if (err) {
		dev_err(&client->dev, "unable to add clk provider\n");
		return err;
	}

	if (initialization_required) {
		/* Synchronize */
		regcache_cache_only(data->regmap, false);
		err = regcache_sync(data->regmap);
		if (err < 0)
			return err;

		err = si5341_finalize_defaults(data);
		if (err < 0)
			return err;
	}

	/* Free the names, clk framework makes copies */
	for (i = 0; i < data->num_synth; ++i)
		 devm_kfree(&client->dev, (void *)synth_clock_names[i]);

	return 0;
}

static const struct i2c_device_id si5341_id[] = {
	{ "si5340", 0 },
	{ "si5341", 1 },
	{ }
};
MODULE_DEVICE_TABLE(i2c, si5341_id);

static const struct of_device_id clk_si5341_of_match[] = {
	{ .compatible = "silabs,si5340" },
	{ .compatible = "silabs,si5341" },
	{ }
};
MODULE_DEVICE_TABLE(of, clk_si5341_of_match);

static struct i2c_driver si5341_driver = {
	.driver = {
		.name = "si5341",
		.of_match_table = clk_si5341_of_match,
	},
	.probe		= si5341_probe,
	.id_table	= si5341_id,
};
module_i2c_driver(si5341_driver);

MODULE_AUTHOR("Mike Looijmans <mike.looijmans@topic.nl>");
MODULE_DESCRIPTION("Si5341 driver");
MODULE_LICENSE("GPL");