/*
* ST Microelectronics SPEAr Pulse Width Modulator driver
*
* Copyright (C) 2012 ST Microelectronics
* Shiraz Hashim <[email protected]>
*
* This file is licensed under the terms of the GNU General Public
* License version 2. This program is licensed "as is" without any
* warranty of any kind, whether express or implied.
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include <linux/types.h>
#define NUM_PWM 4
/* PWM registers and bits definitions */
#define PWMCR 0x00 /* Control Register */
#define PWMCR_PWM_ENABLE 0x1
#define PWMCR_PRESCALE_SHIFT 2
#define PWMCR_MIN_PRESCALE 0x00
#define PWMCR_MAX_PRESCALE 0x3FFF
#define PWMDCR 0x04 /* Duty Cycle Register */
#define PWMDCR_MIN_DUTY 0x0001
#define PWMDCR_MAX_DUTY 0xFFFF
#define PWMPCR 0x08 /* Period Register */
#define PWMPCR_MIN_PERIOD 0x0001
#define PWMPCR_MAX_PERIOD 0xFFFF
/* Following only available on 13xx SoCs */
#define PWMMCR 0x3C /* Master Control Register */
#define PWMMCR_PWM_ENABLE 0x1
/**
* struct spear_pwm_chip - struct representing pwm chip
*
* @mmio_base: base address of pwm chip
* @clk: pointer to clk structure of pwm chip
*/
struct spear_pwm_chip {
void __iomem *mmio_base;
struct clk *clk;
};
static inline struct spear_pwm_chip *to_spear_pwm_chip(struct pwm_chip *chip)
{
return pwmchip_get_drvdata(chip);
}
static inline u32 spear_pwm_readl(struct spear_pwm_chip *chip, unsigned int num,
unsigned long offset)
{
return readl_relaxed(chip->mmio_base + (num << 4) + offset);
}
static inline void spear_pwm_writel(struct spear_pwm_chip *chip,
unsigned int num, unsigned long offset,
unsigned long val)
{
writel_relaxed(val, chip->mmio_base + (num << 4) + offset);
}
static int spear_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
u64 duty_ns, u64 period_ns)
{
struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
u64 val, div, clk_rate;
unsigned long prescale = PWMCR_MIN_PRESCALE, pv, dc;
int ret;
/*
* Find pv, dc and prescale to suit duty_ns and period_ns. This is done
* according to formulas described below:
*
* period_ns = 10^9 * (PRESCALE + 1) * PV / PWM_CLK_RATE
* duty_ns = 10^9 * (PRESCALE + 1) * DC / PWM_CLK_RATE
*
* PV = (PWM_CLK_RATE * period_ns) / (10^9 * (PRESCALE + 1))
* DC = (PWM_CLK_RATE * duty_ns) / (10^9 * (PRESCALE + 1))
*/
clk_rate = clk_get_rate(pc->clk);
while (1) {
div = 1000000000;
div *= 1 + prescale;
val = clk_rate * period_ns;
pv = div64_u64(val, div);
val = clk_rate * duty_ns;
dc = div64_u64(val, div);
/* if duty_ns and period_ns are not achievable then return */
if (pv < PWMPCR_MIN_PERIOD || dc < PWMDCR_MIN_DUTY)
return -EINVAL;
/*
* if pv and dc have crossed their upper limit, then increase
* prescale and recalculate pv and dc.
*/
if (pv > PWMPCR_MAX_PERIOD || dc > PWMDCR_MAX_DUTY) {
if (++prescale > PWMCR_MAX_PRESCALE)
return -EINVAL;
continue;
}
break;
}
/*
* NOTE: the clock to PWM has to be enabled first before writing to the
* registers.
*/
ret = clk_enable(pc->clk);
if (ret)
return ret;
spear_pwm_writel(pc, pwm->hwpwm, PWMCR,
prescale << PWMCR_PRESCALE_SHIFT);
spear_pwm_writel(pc, pwm->hwpwm, PWMDCR, dc);
spear_pwm_writel(pc, pwm->hwpwm, PWMPCR, pv);
clk_disable(pc->clk);
return 0;
}
static int spear_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
int rc = 0;
u32 val;
rc = clk_enable(pc->clk);
if (rc)
return rc;
val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR);
val |= PWMCR_PWM_ENABLE;
spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val);
return 0;
}
static void spear_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct spear_pwm_chip *pc = to_spear_pwm_chip(chip);
u32 val;
val = spear_pwm_readl(pc, pwm->hwpwm, PWMCR);
val &= ~PWMCR_PWM_ENABLE;
spear_pwm_writel(pc, pwm->hwpwm, PWMCR, val);
clk_disable(pc->clk);
}
static int spear_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err;
if (state->polarity != PWM_POLARITY_NORMAL)
return -EINVAL;
if (!state->enabled) {
if (pwm->state.enabled)
spear_pwm_disable(chip, pwm);
return 0;
}
err = spear_pwm_config(chip, pwm, state->duty_cycle, state->period);
if (err)
return err;
if (!pwm->state.enabled)
return spear_pwm_enable(chip, pwm);
return 0;
}
static const struct pwm_ops spear_pwm_ops = {
.apply = spear_pwm_apply,
};
static int spear_pwm_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct pwm_chip *chip;
struct spear_pwm_chip *pc;
int ret;
u32 val;
chip = devm_pwmchip_alloc(&pdev->dev, NUM_PWM, sizeof(*pc));
if (IS_ERR(chip))
return PTR_ERR(chip);
pc = to_spear_pwm_chip(chip);
pc->mmio_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(pc->mmio_base))
return PTR_ERR(pc->mmio_base);
pc->clk = devm_clk_get_prepared(&pdev->dev, NULL);
if (IS_ERR(pc->clk))
return dev_err_probe(&pdev->dev, PTR_ERR(pc->clk),
"Failed to get clock\n");
chip->ops = &spear_pwm_ops;
if (of_device_is_compatible(np, "st,spear1340-pwm")) {
ret = clk_enable(pc->clk);
if (ret)
return dev_err_probe(&pdev->dev, ret,
"Failed to enable clk\n");
/*
* Following enables PWM chip, channels would still be
* enabled individually through their control register
*/
val = readl_relaxed(pc->mmio_base + PWMMCR);
val |= PWMMCR_PWM_ENABLE;
writel_relaxed(val, pc->mmio_base + PWMMCR);
clk_disable(pc->clk);
}
ret = devm_pwmchip_add(&pdev->dev, chip);
if (ret < 0)
return dev_err_probe(&pdev->dev, ret, "pwmchip_add() failed\n");
return 0;
}
static const struct of_device_id spear_pwm_of_match[] = {
{ .compatible = "st,spear320-pwm" },
{ .compatible = "st,spear1340-pwm" },
{ }
};
MODULE_DEVICE_TABLE(of, spear_pwm_of_match);
static struct platform_driver spear_pwm_driver = {
.driver = {
.name = "spear-pwm",
.of_match_table = spear_pwm_of_match,
},
.probe = spear_pwm_probe,
};
module_platform_driver(spear_pwm_driver);
MODULE_DESCRIPTION("ST Microelectronics SPEAr Pulse Width Modulator driver");
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Shiraz Hashim <[email protected]>");
MODULE_AUTHOR("Viresh Kumar <[email protected]>");
MODULE_ALIAS("platform:spear-pwm");
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