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// SPDX-License-Identifier: GPL-2.0-or-later
/*
* Broadcom BCM7038 PWM driver
* Author: Florian Fainelli
*
* Copyright (C) 2015 Broadcom Corporation
*/
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/clk.h>
#include <linux/export.h>
#include <linux/init.h>
#include <linux/io.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/spinlock.h>
#define PWM_CTRL 0x00
#define CTRL_START BIT(0)
#define CTRL_OEB BIT(1)
#define CTRL_FORCE_HIGH BIT(2)
#define CTRL_OPENDRAIN BIT(3)
#define CTRL_CHAN_OFFS 4
#define PWM_CTRL2 0x04
#define CTRL2_OUT_SELECT BIT(0)
#define PWM_CH_SIZE 0x8
#define PWM_CWORD_MSB(ch) (0x08 + ((ch) * PWM_CH_SIZE))
#define PWM_CWORD_LSB(ch) (0x0c + ((ch) * PWM_CH_SIZE))
/* Number of bits for the CWORD value */
#define CWORD_BIT_SIZE 16
/*
* Maximum control word value allowed when variable-frequency PWM is used as a
* clock for the constant-frequency PMW.
*/
#define CONST_VAR_F_MAX 32768
#define CONST_VAR_F_MIN 1
#define PWM_ON(ch) (0x18 + ((ch) * PWM_CH_SIZE))
#define PWM_ON_MIN 1
#define PWM_PERIOD(ch) (0x1c + ((ch) * PWM_CH_SIZE))
#define PWM_PERIOD_MIN 0
#define PWM_ON_PERIOD_MAX 0xff
struct brcmstb_pwm {
void __iomem *base;
struct clk *clk;
struct pwm_chip chip;
};
static inline u32 brcmstb_pwm_readl(struct brcmstb_pwm *p,
unsigned int offset)
{
if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
return __raw_readl(p->base + offset);
else
return readl_relaxed(p->base + offset);
}
static inline void brcmstb_pwm_writel(struct brcmstb_pwm *p, u32 value,
unsigned int offset)
{
if (IS_ENABLED(CONFIG_MIPS) && IS_ENABLED(CONFIG_CPU_BIG_ENDIAN))
__raw_writel(value, p->base + offset);
else
writel_relaxed(value, p->base + offset);
}
static inline struct brcmstb_pwm *to_brcmstb_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct brcmstb_pwm, chip);
}
/*
* Fv is derived from the variable frequency output. The variable frequency
* output is configured using this formula:
*
* W = cword, if cword < 2 ^ 15 else 16-bit 2's complement of cword
*
* Fv = W x 2 ^ -16 x 27Mhz (reference clock)
*
* The period is: (period + 1) / Fv and "on" time is on / (period + 1)
*
* The PWM core framework specifies that the "duty_ns" parameter is in fact the
* "on" time, so this translates directly into our HW programming here.
*/
static int brcmstb_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
u64 duty_ns, u64 period_ns)
{
struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
unsigned long pc, dc, cword = CONST_VAR_F_MAX;
unsigned int channel = pwm->hwpwm;
u32 value;
/*
* If asking for a duty_ns equal to period_ns, we need to substract
* the period value by 1 to make it shorter than the "on" time and
* produce a flat 100% duty cycle signal, and max out the "on" time
*/
if (duty_ns == period_ns) {
dc = PWM_ON_PERIOD_MAX;
pc = PWM_ON_PERIOD_MAX - 1;
goto done;
}
while (1) {
u64 rate;
/*
* Calculate the base rate from base frequency and current
* cword
*/
rate = (u64)clk_get_rate(p->clk) * (u64)cword;
rate >>= CWORD_BIT_SIZE;
pc = mul_u64_u64_div_u64(period_ns, rate, NSEC_PER_SEC);
dc = mul_u64_u64_div_u64(duty_ns + 1, rate, NSEC_PER_SEC);
/*
* We can be called with separate duty and period updates,
* so do not reject dc == 0 right away
*/
if (pc == PWM_PERIOD_MIN || (dc < PWM_ON_MIN && duty_ns))
return -EINVAL;
/* We converged on a calculation */
if (pc <= PWM_ON_PERIOD_MAX && dc <= PWM_ON_PERIOD_MAX)
break;
/*
* The cword needs to be a power of 2 for the variable
* frequency generator to output a 50% duty cycle variable
* frequency which is used as input clock to the fixed
* frequency generator.
*/
cword >>= 1;
/*
* Desired periods are too large, we do not have a divider
* for them
*/
if (cword < CONST_VAR_F_MIN)
return -EINVAL;
}
done:
/*
* Configure the defined "cword" value to have the variable frequency
* generator output a base frequency for the constant frequency
* generator to derive from.
*/
brcmstb_pwm_writel(p, cword >> 8, PWM_CWORD_MSB(channel));
brcmstb_pwm_writel(p, cword & 0xff, PWM_CWORD_LSB(channel));
/* Select constant frequency signal output */
value = brcmstb_pwm_readl(p, PWM_CTRL2);
value |= CTRL2_OUT_SELECT << (channel * CTRL_CHAN_OFFS);
brcmstb_pwm_writel(p, value, PWM_CTRL2);
/* Configure on and period value */
brcmstb_pwm_writel(p, pc, PWM_PERIOD(channel));
brcmstb_pwm_writel(p, dc, PWM_ON(channel));
return 0;
}
static inline void brcmstb_pwm_enable_set(struct brcmstb_pwm *p,
unsigned int channel, bool enable)
{
unsigned int shift = channel * CTRL_CHAN_OFFS;
u32 value;
value = brcmstb_pwm_readl(p, PWM_CTRL);
if (enable) {
value &= ~(CTRL_OEB << shift);
value |= (CTRL_START | CTRL_OPENDRAIN) << shift;
} else {
value &= ~((CTRL_START | CTRL_OPENDRAIN) << shift);
value |= CTRL_OEB << shift;
}
brcmstb_pwm_writel(p, value, PWM_CTRL);
}
static int brcmstb_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct brcmstb_pwm *p = to_brcmstb_pwm(chip);
int err;
if (state->polarity != PWM_POLARITY_NORMAL)
return -EINVAL;
if (!state->enabled) {
if (pwm->state.enabled)
brcmstb_pwm_enable_set(p, pwm->hwpwm, false);
return 0;
}
err = brcmstb_pwm_config(chip, pwm, state->duty_cycle, state->period);
if (err)
return err;
if (!pwm->state.enabled)
brcmstb_pwm_enable_set(p, pwm->hwpwm, true);
return 0;
}
static const struct pwm_ops brcmstb_pwm_ops = {
.apply = brcmstb_pwm_apply,
};
static const struct of_device_id brcmstb_pwm_of_match[] = {
{ .compatible = "brcm,bcm7038-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, brcmstb_pwm_of_match);
static int brcmstb_pwm_probe(struct platform_device *pdev)
{
struct brcmstb_pwm *p;
int ret;
p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
if (!p)
return -ENOMEM;
p->clk = devm_clk_get_enabled(&pdev->dev, NULL);
if (IS_ERR(p->clk))
return dev_err_probe(&pdev->dev, PTR_ERR(p->clk),
"failed to obtain clock\n");
platform_set_drvdata(pdev, p);
p->chip.dev = &pdev->dev;
p->chip.ops = &brcmstb_pwm_ops;
p->chip.npwm = 2;
p->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(p->base))
return PTR_ERR(p->base);
ret = devm_pwmchip_add(&pdev->dev, &p->chip);
if (ret)
return dev_err_probe(&pdev->dev, ret, "failed to add PWM chip\n");
return 0;
}
static int brcmstb_pwm_suspend(struct device *dev)
{
struct brcmstb_pwm *p = dev_get_drvdata(dev);
clk_disable_unprepare(p->clk);
return 0;
}
static int brcmstb_pwm_resume(struct device *dev)
{
struct brcmstb_pwm *p = dev_get_drvdata(dev);
return clk_prepare_enable(p->clk);
}
static DEFINE_SIMPLE_DEV_PM_OPS(brcmstb_pwm_pm_ops, brcmstb_pwm_suspend,
brcmstb_pwm_resume);
static struct platform_driver brcmstb_pwm_driver = {
.probe = brcmstb_pwm_probe,
.driver = {
.name = "pwm-brcmstb",
.of_match_table = brcmstb_pwm_of_match,
.pm = pm_ptr(&brcmstb_pwm_pm_ops),
},
};
module_platform_driver(brcmstb_pwm_driver);
MODULE_AUTHOR("Florian Fainelli <f.fainelli@gmail.com>");
MODULE_DESCRIPTION("Broadcom STB PWM driver");
MODULE_ALIAS("platform:pwm-brcmstb");
MODULE_LICENSE("GPL");