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/*
* Driver for Allwinner sun4i Pulse Width Modulation Controller
*
* Copyright (C) 2014 Alexandre Belloni <alexandre.belloni@free-electrons.com>
*
* Licensed under GPLv2.
*/
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/jiffies.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/time.h>
#define PWM_CTRL_REG 0x0
#define PWM_CH_PRD_BASE 0x4
#define PWM_CH_PRD_OFFSET 0x4
#define PWM_CH_PRD(ch) (PWM_CH_PRD_BASE + PWM_CH_PRD_OFFSET * (ch))
#define PWMCH_OFFSET 15
#define PWM_PRESCAL_MASK GENMASK(3, 0)
#define PWM_PRESCAL_OFF 0
#define PWM_EN BIT(4)
#define PWM_ACT_STATE BIT(5)
#define PWM_CLK_GATING BIT(6)
#define PWM_MODE BIT(7)
#define PWM_PULSE BIT(8)
#define PWM_BYPASS BIT(9)
#define PWM_RDY_BASE 28
#define PWM_RDY_OFFSET 1
#define PWM_RDY(ch) BIT(PWM_RDY_BASE + PWM_RDY_OFFSET * (ch))
#define PWM_PRD(prd) (((prd) - 1) << 16)
#define PWM_PRD_MASK GENMASK(15, 0)
#define PWM_DTY_MASK GENMASK(15, 0)
#define PWM_REG_PRD(reg) ((((reg) >> 16) & PWM_PRD_MASK) + 1)
#define PWM_REG_DTY(reg) ((reg) & PWM_DTY_MASK)
#define PWM_REG_PRESCAL(reg, chan) (((reg) >> ((chan) * PWMCH_OFFSET)) & PWM_PRESCAL_MASK)
#define BIT_CH(bit, chan) ((bit) << ((chan) * PWMCH_OFFSET))
static const u32 prescaler_table[] = {
120,
180,
240,
360,
480,
0,
0,
0,
12000,
24000,
36000,
48000,
72000,
0,
0,
0, /* Actually 1 but tested separately */
};
struct sun4i_pwm_data {
bool has_prescaler_bypass;
bool has_rdy;
unsigned int npwm;
};
struct sun4i_pwm_chip {
struct pwm_chip chip;
struct clk *clk;
void __iomem *base;
spinlock_t ctrl_lock;
const struct sun4i_pwm_data *data;
unsigned long next_period[2];
bool needs_delay[2];
};
static inline struct sun4i_pwm_chip *to_sun4i_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct sun4i_pwm_chip, chip);
}
static inline u32 sun4i_pwm_readl(struct sun4i_pwm_chip *chip,
unsigned long offset)
{
return readl(chip->base + offset);
}
static inline void sun4i_pwm_writel(struct sun4i_pwm_chip *chip,
u32 val, unsigned long offset)
{
writel(val, chip->base + offset);
}
static void sun4i_pwm_get_state(struct pwm_chip *chip,
struct pwm_device *pwm,
struct pwm_state *state)
{
struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
u64 clk_rate, tmp;
u32 val;
unsigned int prescaler;
clk_rate = clk_get_rate(sun4i_pwm->clk);
val = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
if ((val == PWM_PRESCAL_MASK) && sun4i_pwm->data->has_prescaler_bypass)
prescaler = 1;
else
prescaler = prescaler_table[PWM_REG_PRESCAL(val, pwm->hwpwm)];
if (prescaler == 0)
return;
if (val & BIT_CH(PWM_ACT_STATE, pwm->hwpwm))
state->polarity = PWM_POLARITY_NORMAL;
else
state->polarity = PWM_POLARITY_INVERSED;
if (val & BIT_CH(PWM_CLK_GATING | PWM_EN, pwm->hwpwm))
state->enabled = true;
else
state->enabled = false;
val = sun4i_pwm_readl(sun4i_pwm, PWM_CH_PRD(pwm->hwpwm));
tmp = prescaler * NSEC_PER_SEC * PWM_REG_DTY(val);
state->duty_cycle = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
tmp = prescaler * NSEC_PER_SEC * PWM_REG_PRD(val);
state->period = DIV_ROUND_CLOSEST_ULL(tmp, clk_rate);
}
static int sun4i_pwm_calculate(struct sun4i_pwm_chip *sun4i_pwm,
struct pwm_state *state,
u32 *dty, u32 *prd, unsigned int *prsclr)
{
u64 clk_rate, div = 0;
unsigned int pval, prescaler = 0;
clk_rate = clk_get_rate(sun4i_pwm->clk);
if (sun4i_pwm->data->has_prescaler_bypass) {
/* First, test without any prescaler when available */
prescaler = PWM_PRESCAL_MASK;
pval = 1;
/*
* When not using any prescaler, the clock period in nanoseconds
* is not an integer so round it half up instead of
* truncating to get less surprising values.
*/
div = clk_rate * state->period + NSEC_PER_SEC / 2;
do_div(div, NSEC_PER_SEC);
if (div - 1 > PWM_PRD_MASK)
prescaler = 0;
}
if (prescaler == 0) {
/* Go up from the first divider */
for (prescaler = 0; prescaler < PWM_PRESCAL_MASK; prescaler++) {
if (!prescaler_table[prescaler])
continue;
pval = prescaler_table[prescaler];
div = clk_rate;
do_div(div, pval);
div = div * state->period;
do_div(div, NSEC_PER_SEC);
if (div - 1 <= PWM_PRD_MASK)
break;
}
if (div - 1 > PWM_PRD_MASK)
return -EINVAL;
}
*prd = div;
div *= state->duty_cycle;
do_div(div, state->period);
*dty = div;
*prsclr = prescaler;
div = (u64)pval * NSEC_PER_SEC * *prd;
state->period = DIV_ROUND_CLOSEST_ULL(div, clk_rate);
div = (u64)pval * NSEC_PER_SEC * *dty;
state->duty_cycle = DIV_ROUND_CLOSEST_ULL(div, clk_rate);
return 0;
}
static int sun4i_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct sun4i_pwm_chip *sun4i_pwm = to_sun4i_pwm_chip(chip);
struct pwm_state cstate;
u32 ctrl;
int ret;
unsigned int delay_us;
unsigned long now;
pwm_get_state(pwm, &cstate);
if (!cstate.enabled) {
ret = clk_prepare_enable(sun4i_pwm->clk);
if (ret) {
dev_err(chip->dev, "failed to enable PWM clock\n");
return ret;
}
}
spin_lock(&sun4i_pwm->ctrl_lock);
ctrl = sun4i_pwm_readl(sun4i_pwm, PWM_CTRL_REG);
if ((cstate.period != state->period) ||
(cstate.duty_cycle != state->duty_cycle)) {
u32 period, duty, val;
unsigned int prescaler;
ret = sun4i_pwm_calculate(sun4i_pwm, state,
&duty, &period, &prescaler);
if (ret) {
dev_err(chip->dev, "period exceeds the maximum value\n");
spin_unlock(&sun4i_pwm->ctrl_lock);
if (!cstate.enabled)
clk_disable_unprepare(sun4i_pwm->clk);
return ret;
}
if (PWM_REG_PRESCAL(ctrl, pwm->hwpwm) != prescaler) {
/* Prescaler changed, the clock has to be gated */
ctrl &= ~BIT_CH(PWM_CLK_GATING, pwm->hwpwm);
sun4i_pwm_writel(sun4i_pwm, ctrl, PWM_CTRL_REG);
ctrl &= ~BIT_CH(PWM_PRESCAL_MASK, pwm->hwpwm);
ctrl |= BIT_CH(prescaler, pwm->hwpwm);
}
val = (duty & PWM_DTY_MASK) | PWM_PRD(period);
sun4i_pwm_writel(sun4i_pwm, val, PWM_CH_PRD(pwm->hwpwm));
sun4i_pwm->next_period[pwm->hwpwm] = jiffies +
usecs_to_jiffies(cstate.period / 1000 + 1);
sun4i_pwm->needs_delay[pwm->hwpwm] = true;
}
if (state->polarity != PWM_POLARITY_NORMAL)
ctrl &= ~BIT_CH(PWM_ACT_STATE, pwm->hwpwm);
else
ctrl |= BIT_CH(PWM_ACT_STATE, pwm->hwpwm
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