Commit 1459c837 authored by Soren Brinkmann's avatar Soren Brinkmann Committed by Mike Turquette

clk: si570: Add a driver for SI570 oscillators

Add a driver for SILabs 570, 571, 598, 599 programmable oscillators.
The devices generate low-jitter clock signals and are reprogrammable via
an I2C interface.
Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarSoren Brinkmann <soren.brinkmann@xilinx.com>
Signed-off-by: default avatarMike Turquette <mturquette@linaro.org>
parent 3a5aec24
Binding for Silicon Labs 570, 571, 598 and 599 programmable
I2C clock generators.
Reference
This binding uses the common clock binding[1]. Details about the devices can be
found in the data sheets[2][3].
[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
[2] Si570/571 Data Sheet
http://www.silabs.com/Support%20Documents/TechnicalDocs/si570.pdf
[3] Si598/599 Data Sheet
http://www.silabs.com/Support%20Documents/TechnicalDocs/si598-99.pdf
Required properties:
- compatible: Shall be one of "silabs,si570", "silabs,si571",
"silabs,si598", "silabs,si599"
- reg: I2C device address.
- #clock-cells: From common clock bindings: Shall be 0.
- factory-fout: Factory set default frequency. This frequency is part specific.
The correct frequency for the part used has to be provided in
order to generate the correct output frequencies. For more
details, please refer to the data sheet.
- temperature-stability: Temperature stability of the device in PPM. Should be
one of: 7, 20, 50 or 100.
Optional properties:
- clock-output-names: From common clock bindings. Recommended to be "si570".
- clock-frequency: Output frequency to generate. This defines the output
frequency set during boot. It can be reprogrammed during
runtime through the common clock framework.
Example:
si570: clock-generator@5d {
#clock-cells = <0>;
compatible = "silabs,si570";
temperature-stability = <50>;
reg = <0x5d>;
factory-fout = <156250000>;
};
......@@ -64,6 +64,16 @@ config COMMON_CLK_SI5351
This driver supports Silicon Labs 5351A/B/C programmable clock
generators.
config COMMON_CLK_SI570
tristate "Clock driver for SiLabs 570 and compatible devices"
depends on I2C
depends on OF
select REGMAP_I2C
help
---help---
This driver supports Silicon Labs 570/571/598/599 programmable
clock generators.
config COMMON_CLK_S2MPS11
tristate "Clock driver for S2MPS11 MFD"
depends on MFD_SEC_CORE
......
......@@ -45,6 +45,7 @@ obj-$(CONFIG_COMMON_CLK_AXI_CLKGEN) += clk-axi-clkgen.o
obj-$(CONFIG_COMMON_CLK_WM831X) += clk-wm831x.o
obj-$(CONFIG_COMMON_CLK_MAX77686) += clk-max77686.o
obj-$(CONFIG_COMMON_CLK_SI5351) += clk-si5351.o
obj-$(CONFIG_COMMON_CLK_SI570) += clk-si570.o
obj-$(CONFIG_COMMON_CLK_S2MPS11) += clk-s2mps11.o
obj-$(CONFIG_CLK_TWL6040) += clk-twl6040.o
obj-$(CONFIG_CLK_PPC_CORENET) += clk-ppc-corenet.o
/*
* Driver for Silicon Labs Si570/Si571 Programmable XO/VCXO
*
* Copyright (C) 2010, 2011 Ericsson AB.
* Copyright (C) 2011 Guenter Roeck.
* Copyright (C) 2011 - 2013 Xilinx Inc.
*
* Author: Guenter Roeck <guenter.roeck@ericsson.com>
* Sören Brinkmann <soren.brinkmann@xilinx.com>
*
* 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>
/* Si570 registers */
#define SI570_REG_HS_N1 7
#define SI570_REG_N1_RFREQ0 8
#define SI570_REG_RFREQ1 9
#define SI570_REG_RFREQ2 10
#define SI570_REG_RFREQ3 11
#define SI570_REG_RFREQ4 12
#define SI570_REG_CONTROL 135
#define SI570_REG_FREEZE_DCO 137
#define SI570_DIV_OFFSET_7PPM 6
#define HS_DIV_SHIFT 5
#define HS_DIV_MASK 0xe0
#define HS_DIV_OFFSET 4
#define N1_6_2_MASK 0x1f
#define N1_1_0_MASK 0xc0
#define RFREQ_37_32_MASK 0x3f
#define SI570_MIN_FREQ 10000000L
#define SI570_MAX_FREQ 1417500000L
#define SI598_MAX_FREQ 525000000L
#define FDCO_MIN 4850000000LL
#define FDCO_MAX 5670000000LL
#define SI570_CNTRL_RECALL (1 << 0)
#define SI570_CNTRL_FREEZE_M (1 << 5)
#define SI570_CNTRL_NEWFREQ (1 << 6)
#define SI570_FREEZE_DCO (1 << 4)
/**
* struct clk_si570:
* @hw: Clock hw struct
* @regmap: Device's regmap
* @div_offset: Rgister offset for dividers
* @max_freq: Maximum frequency for this device
* @fxtal: Factory xtal frequency
* @n1: Clock divider N1
* @hs_div: Clock divider HSDIV
* @rfreq: Clock multiplier RFREQ
* @frequency: Current output frequency
* @i2c_client: I2C client pointer
*/
struct clk_si570 {
struct clk_hw hw;
struct regmap *regmap;
unsigned int div_offset;
u64 max_freq;
u64 fxtal;
unsigned int n1;
unsigned int hs_div;
u64 rfreq;
u64 frequency;
struct i2c_client *i2c_client;
};
#define to_clk_si570(_hw) container_of(_hw, struct clk_si570, hw)
enum clk_si570_variant {
si57x,
si59x
};
/**
* si570_get_divs() - Read clock dividers from HW
* @data: Pointer to struct clk_si570
* @rfreq: Fractional multiplier (output)
* @n1: Divider N1 (output)
* @hs_div: Divider HSDIV (output)
* Returns 0 on success, negative errno otherwise.
*
* Retrieve clock dividers and multipliers from the HW.
*/
static int si570_get_divs(struct clk_si570 *data, u64 *rfreq,
unsigned int *n1, unsigned int *hs_div)
{
int err;
u8 reg[6];
u64 tmp;
err = regmap_bulk_read(data->regmap, SI570_REG_HS_N1 + data->div_offset,
reg, ARRAY_SIZE(reg));
if (err)
return err;
*hs_div = ((reg[0] & HS_DIV_MASK) >> HS_DIV_SHIFT) + HS_DIV_OFFSET;
*n1 = ((reg[0] & N1_6_2_MASK) << 2) + ((reg[1] & N1_1_0_MASK) >> 6) + 1;
/* Handle invalid cases */
if (*n1 > 1)
*n1 &= ~1;
tmp = reg[1] & RFREQ_37_32_MASK;
tmp = (tmp << 8) + reg[2];
tmp = (tmp << 8) + reg[3];
tmp = (tmp << 8) + reg[4];
tmp = (tmp << 8) + reg[5];
*rfreq = tmp;
return 0;
}
/**
* si570_get_defaults() - Get default values
* @data: Driver data structure
* @fout: Factory frequency output
* Returns 0 on success, negative errno otherwise.
*/
static int si570_get_defaults(struct clk_si570 *data, u64 fout)
{
int err;
u64 fdco;
regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_RECALL);
err = si570_get_divs(data, &data->rfreq, &data->n1, &data->hs_div);
if (err)
return err;
/*
* Accept optional precision loss to avoid arithmetic overflows.
* Acceptable per Silicon Labs Application Note AN334.
*/
fdco = fout * data->n1 * data->hs_div;
if (fdco >= (1LL << 36))
data->fxtal = div64_u64(fdco << 24, data->rfreq >> 4);
else
data->fxtal = div64_u64(fdco << 28, data->rfreq);
data->frequency = fout;
return 0;
}
/**
* si570_update_rfreq() - Update clock multiplier
* @data: Driver data structure
* Passes on regmap_bulk_write() return value.
*/
static int si570_update_rfreq(struct clk_si570 *data)
{
u8 reg[5];
reg[0] = ((data->n1 - 1) << 6) |
((data->rfreq >> 32) & RFREQ_37_32_MASK);
reg[1] = (data->rfreq >> 24) & 0xff;
reg[2] = (data->rfreq >> 16) & 0xff;
reg[3] = (data->rfreq >> 8) & 0xff;
reg[4] = data->rfreq & 0xff;
return regmap_bulk_write(data->regmap, SI570_REG_N1_RFREQ0 +
data->div_offset, reg, ARRAY_SIZE(reg));
}
/**
* si570_calc_divs() - Caluclate clock dividers
* @frequency: Target frequency
* @data: Driver data structure
* @out_rfreq: RFREG fractional multiplier (output)
* @out_n1: Clock divider N1 (output)
* @out_hs_div: Clock divider HSDIV (output)
* Returns 0 on success, negative errno otherwise.
*
* Calculate the clock dividers (@out_hs_div, @out_n1) and clock multiplier
* (@out_rfreq) for a given target @frequency.
*/
static int si570_calc_divs(unsigned long frequency, struct clk_si570 *data,
u64 *out_rfreq, unsigned int *out_n1, unsigned int *out_hs_div)
{
int i;
unsigned int n1, hs_div;
u64 fdco, best_fdco = ULLONG_MAX;
static const uint8_t si570_hs_div_values[] = { 11, 9, 7, 6, 5, 4 };
for (i = 0; i < ARRAY_SIZE(si570_hs_div_values); i++) {
hs_div = si570_hs_div_values[i];
/* Calculate lowest possible value for n1 */
n1 = div_u64(div_u64(FDCO_MIN, hs_div), frequency);
if (!n1 || (n1 & 1))
n1++;
while (n1 <= 128) {
fdco = (u64)frequency * (u64)hs_div * (u64)n1;
if (fdco > FDCO_MAX)
break;
if (fdco >= FDCO_MIN && fdco < best_fdco) {
*out_n1 = n1;
*out_hs_div = hs_div;
*out_rfreq = div64_u64(fdco << 28, data->fxtal);
best_fdco = fdco;
}
n1 += (n1 == 1 ? 1 : 2);
}
}
if (best_fdco == ULLONG_MAX)
return -EINVAL;
return 0;
}
static unsigned long si570_recalc_rate(struct clk_hw *hw,
unsigned long parent_rate)
{
int err;
u64 rfreq, rate;
unsigned int n1, hs_div;
struct clk_si570 *data = to_clk_si570(hw);
err = si570_get_divs(data, &rfreq, &n1, &hs_div);
if (err) {
dev_err(&data->i2c_client->dev, "unable to recalc rate\n");
return data->frequency;
}
rfreq = div_u64(rfreq, hs_div * n1);
rate = (data->fxtal * rfreq) >> 28;
return rate;
}
static long si570_round_rate(struct clk_hw *hw, unsigned long rate,
unsigned long *parent_rate)
{
int err;
u64 rfreq;
unsigned int n1, hs_div;
struct clk_si570 *data = to_clk_si570(hw);
if (!rate)
return 0;
if (div64_u64(abs(rate - data->frequency) * 10000LL,
data->frequency) < 35) {
rfreq = div64_u64((data->rfreq * rate) +
div64_u64(data->frequency, 2), data->frequency);
n1 = data->n1;
hs_div = data->hs_div;
} else {
err = si570_calc_divs(rate, data, &rfreq, &n1, &hs_div);
if (err) {
dev_err(&data->i2c_client->dev,
"unable to round rate\n");
return 0;
}
}
return rate;
}
/**
* si570_set_frequency() - Adjust output frequency
* @data: Driver data structure
* @frequency: Target frequency
* Returns 0 on success.
*
* Update output frequency for big frequency changes (> 3,500 ppm).
*/
static int si570_set_frequency(struct clk_si570 *data, unsigned long frequency)
{
int err;
err = si570_calc_divs(frequency, data, &data->rfreq, &data->n1,
&data->hs_div);
if (err)
return err;
/*
* The DCO reg should be accessed with a read-modify-write operation
* per AN334
*/
regmap_write(data->regmap, SI570_REG_FREEZE_DCO, SI570_FREEZE_DCO);
regmap_write(data->regmap, SI570_REG_HS_N1 + data->div_offset,
((data->hs_div - HS_DIV_OFFSET) << HS_DIV_SHIFT) |
(((data->n1 - 1) >> 2) & N1_6_2_MASK));
si570_update_rfreq(data);
regmap_write(data->regmap, SI570_REG_FREEZE_DCO, 0);
regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_NEWFREQ);
/* Applying a new frequency can take up to 10ms */
usleep_range(10000, 12000);
return 0;
}
/**
* si570_set_frequency_small() - Adjust output frequency
* @data: Driver data structure
* @frequency: Target frequency
* Returns 0 on success.
*
* Update output frequency for small frequency changes (< 3,500 ppm).
*/
static int si570_set_frequency_small(struct clk_si570 *data,
unsigned long frequency)
{
/*
* This is a re-implementation of DIV_ROUND_CLOSEST
* using the div64_u64 function lieu of letting the compiler
* insert EABI calls
*/
data->rfreq = div64_u64((data->rfreq * frequency) +
div_u64(data->frequency, 2), data->frequency);
regmap_write(data->regmap, SI570_REG_CONTROL, SI570_CNTRL_FREEZE_M);
si570_update_rfreq(data);
regmap_write(data->regmap, SI570_REG_CONTROL, 0);
/* Applying a new frequency (small change) can take up to 100us */
usleep_range(100, 200);
return 0;
}
static int si570_set_rate(struct clk_hw *hw, unsigned long rate,
unsigned long parent_rate)
{
struct clk_si570 *data = to_clk_si570(hw);
struct i2c_client *client = data->i2c_client;
int err;
if (rate < SI570_MIN_FREQ || rate > data->max_freq) {
dev_err(&client->dev,
"requested frequency %lu Hz is out of range\n", rate);
return -EINVAL;
}
if (div64_u64(abs(rate - data->frequency) * 10000LL,
data->frequency) < 35)
err = si570_set_frequency_small(data, rate);
else
err = si570_set_frequency(data, rate);
if (err)
return err;
data->frequency = rate;
return 0;
}
static const struct clk_ops si570_clk_ops = {
.recalc_rate = si570_recalc_rate,
.round_rate = si570_round_rate,
.set_rate = si570_set_rate,
};
static bool si570_regmap_is_volatile(struct device *dev, unsigned int reg)
{
switch (reg) {
case SI570_REG_CONTROL:
return true;
default:
return false;
}
}
static bool si570_regmap_is_writeable(struct device *dev, unsigned int reg)
{
switch (reg) {
case SI570_REG_HS_N1 ... (SI570_REG_RFREQ4 + SI570_DIV_OFFSET_7PPM):
case SI570_REG_CONTROL:
case SI570_REG_FREEZE_DCO:
return true;
default:
return false;
}
}
static struct regmap_config si570_regmap_config = {
.reg_bits = 8,
.val_bits = 8,
.cache_type = REGCACHE_RBTREE,
.max_register = 137,
.writeable_reg = si570_regmap_is_writeable,
.volatile_reg = si570_regmap_is_volatile,
};
static int si570_probe(struct i2c_client *client,
const struct i2c_device_id *id)
{
struct clk_si570 *data;
struct clk_init_data init;
struct clk *clk;
u32 initial_fout, factory_fout, stability;
int err;
enum clk_si570_variant variant = id->driver_data;
data = devm_kzalloc(&client->dev, sizeof(*data), GFP_KERNEL);
if (!data)
return -ENOMEM;
init.ops = &si570_clk_ops;
init.flags = CLK_IS_ROOT;
init.num_parents = 0;
data->hw.init = &init;
data->i2c_client = client;
if (variant == si57x) {
err = of_property_read_u32(client->dev.of_node,
"temperature-stability", &stability);
if (err) {
dev_err(&client->dev,
"'temperature-stability' property missing\n");
return err;
}
/* adjust register offsets for 7ppm devices */
if (stability == 7)
data->div_offset = SI570_DIV_OFFSET_7PPM;
data->max_freq = SI570_MAX_FREQ;
} else {
data->max_freq = SI598_MAX_FREQ;
}
if (of_property_read_string(client->dev.of_node, "clock-output-names",
&init.name))
init.name = client->dev.of_node->name;
err = of_property_read_u32(client->dev.of_node, "factory-fout",
&factory_fout);
if (err) {
dev_err(&client->dev, "'factory-fout' property missing\n");
return err;
}
data->regmap = devm_regmap_init_i2c(client, &si570_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);
err = si570_get_defaults(data, factory_fout);
if (err)
return err;
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;
}
/* Read the requested initial output frequency from device tree */
if (!of_property_read_u32(client->dev.of_node, "clock-frequency",
&initial_fout)) {
err = clk_set_rate(clk, initial_fout);
if (err) {
of_clk_del_provider(client->dev.of_node);
return err;
}
}
/* Display a message indicating that we've successfully registered */
dev_info(&client->dev, "registered, current frequency %llu Hz\n",
data->frequency);
return 0;
}
static int si570_remove(struct i2c_client *client)
{
of_clk_del_provider(client->dev.of_node);
return 0;
}
static const struct i2c_device_id si570_id[] = {
{ "si570", si57x },
{ "si571", si57x },
{ "si598", si59x },
{ "si599", si59x },
{ }
};
MODULE_DEVICE_TABLE(i2c, si570_id);
static const struct of_device_id clk_si570_of_match[] = {
{ .compatible = "silabs,si570" },
{ .compatible = "silabs,si571" },
{ .compatible = "silabs,si598" },
{ .compatible = "silabs,si599" },
{ },
};
MODULE_DEVICE_TABLE(of, clk_si570_of_match);
static struct i2c_driver si570_driver = {
.driver = {
.name = "si570",
.of_match_table = of_match_ptr(clk_si570_of_match),
},
.probe = si570_probe,
.remove = si570_remove,
.id_table = si570_id,
};
module_i2c_driver(si570_driver);
MODULE_AUTHOR("Guenter Roeck <guenter.roeck@ericsson.com>");
MODULE_AUTHOR("Soeren Brinkmann <soren.brinkmann@xilinx.com");
MODULE_DESCRIPTION("Si570 driver");
MODULE_LICENSE("GPL");
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