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linux/drivers/pwm/pwm-stmpe.c
Uwe Kleine-König b2c71e9f8d pwm: stmpe: Handle errors when disabling the signal 
Before the pwm framework implementedatomic updates (with the .apply()
callback) the .disable() callback returned void. This is still visible
in the stmpe driver which drops errors in the disable path.

Improve the driver to forward failures in stmpe_24xx_pwm_disable() to
the caller of pwm_apply_state().

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2023-07-28 09:49:18 +02:00

337 lines
7.5 KiB
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// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2016 Linaro Ltd.
*
* Author: Linus Walleij <linus.walleij@linaro.org>
*/
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/mfd/stmpe.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#include <linux/slab.h>
#define STMPE24XX_PWMCS 0x30
#define PWMCS_EN_PWM0 BIT(0)
#define PWMCS_EN_PWM1 BIT(1)
#define PWMCS_EN_PWM2 BIT(2)
#define STMPE24XX_PWMIC0 0x38
#define STMPE24XX_PWMIC1 0x39
#define STMPE24XX_PWMIC2 0x3a
#define STMPE_PWM_24XX_PINBASE 21
struct stmpe_pwm {
struct stmpe *stmpe;
struct pwm_chip chip;
u8 last_duty;
};
static inline struct stmpe_pwm *to_stmpe_pwm(struct pwm_chip *chip)
{
return container_of(chip, struct stmpe_pwm, chip);
}
static int stmpe_24xx_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
u8 value;
int ret;
ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
if (ret < 0) {
dev_err(chip->dev, "error reading PWM#%u control\n",
pwm->hwpwm);
return ret;
}
value = ret | BIT(pwm->hwpwm);
ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
if (ret) {
dev_err(chip->dev, "error writing PWM#%u control\n",
pwm->hwpwm);
return ret;
}
return 0;
}
static int stmpe_24xx_pwm_disable(struct pwm_chip *chip,
struct pwm_device *pwm)
{
struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
u8 value;
int ret;
ret = stmpe_reg_read(stmpe_pwm->stmpe, STMPE24XX_PWMCS);
if (ret < 0) {
dev_err(chip->dev, "error reading PWM#%u control\n",
pwm->hwpwm);
return ret;
}
value = ret & ~BIT(pwm->hwpwm);
ret = stmpe_reg_write(stmpe_pwm->stmpe, STMPE24XX_PWMCS, value);
if (ret)
dev_err(chip->dev, "error writing PWM#%u control\n",
pwm->hwpwm);
return ret;
}
/* STMPE 24xx PWM instructions */
#define SMAX 0x007f
#define SMIN 0x00ff
#define GTS 0x0000
#define LOAD BIT(14) /* Only available on 2403 */
#define RAMPUP 0x0000
#define RAMPDOWN BIT(7)
#define PRESCALE_512 BIT(14)
#define STEPTIME_1 BIT(8)
#define BRANCH (BIT(15) | BIT(13))
static int stmpe_24xx_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct stmpe_pwm *stmpe_pwm = to_stmpe_pwm(chip);
unsigned int i, pin;
u16 program[3] = {
SMAX,
GTS,
GTS,
};
u8 offset;
int ret;
/* Make sure we are disabled */
if (pwm_is_enabled(pwm)) {
ret = stmpe_24xx_pwm_disable(chip, pwm);
if (ret)
return ret;
} else {
/* Connect the PWM to the pin */
pin = pwm->hwpwm;
/* On STMPE2401 and 2403 pins 21,22,23 are used */
if (stmpe_pwm->stmpe->partnum == STMPE2401 ||
stmpe_pwm->stmpe->partnum == STMPE2403)
pin += STMPE_PWM_24XX_PINBASE;
ret = stmpe_set_altfunc(stmpe_pwm->stmpe, BIT(pin),
STMPE_BLOCK_PWM);
if (ret) {
dev_err(chip->dev, "unable to connect PWM#%u to pin\n",
pwm->hwpwm);
return ret;
}
}
/* STMPE24XX */
switch (pwm->hwpwm) {
case 0:
offset = STMPE24XX_PWMIC0;
break;
case 1:
offset = STMPE24XX_PWMIC1;
break;
case 2:
offset = STMPE24XX_PWMIC2;
break;
default:
/* Should not happen as npwm is 3 */
return -ENODEV;
}
dev_dbg(chip->dev, "PWM#%u: config duty %d ns, period %d ns\n",
pwm->hwpwm, duty_ns, period_ns);
if (duty_ns == 0) {
if (stmpe_pwm->stmpe->partnum == STMPE2401)
program[0] = SMAX; /* off all the time */
if (stmpe_pwm->stmpe->partnum == STMPE2403)
program[0] = LOAD | 0xff; /* LOAD 0xff */
stmpe_pwm->last_duty = 0x00;
} else if (duty_ns == period_ns) {
if (stmpe_pwm->stmpe->partnum == STMPE2401)
program[0] = SMIN; /* on all the time */
if (stmpe_pwm->stmpe->partnum == STMPE2403)
program[0] = LOAD | 0x00; /* LOAD 0x00 */
stmpe_pwm->last_duty = 0xff;
} else {
u8 value, last = stmpe_pwm->last_duty;
unsigned long duty;
/*
* Counter goes from 0x00 to 0xff repeatedly at 32768 Hz,
* (means a period of 30517 ns) then this is compared to the
* counter from the ramp, if this is >= PWM counter the output
* is high. With LOAD we can define how much of the cycle it
* is on.
*
* Prescale = 0 -> 2 kHz -> T = 1/f = 488281.25 ns
*/
/* Scale to 0..0xff */
duty = duty_ns * 256;
duty = DIV_ROUND_CLOSEST(duty, period_ns);
value = duty;
if (value == last) {
/* Run the old program */
if (pwm_is_enabled(pwm))
stmpe_24xx_pwm_enable(chip, pwm);
return 0;
} else if (stmpe_pwm->stmpe->partnum == STMPE2403) {
/* STMPE2403 can simply set the right PWM value */
program[0] = LOAD | value;
program[1] = 0x0000;
} else if (stmpe_pwm->stmpe->partnum == STMPE2401) {
/* STMPE2401 need a complex program */
u16 incdec = 0x0000;
if (last < value)
/* Count up */
incdec = RAMPUP | (value - last);
else
/* Count down */
incdec = RAMPDOWN | (last - value);
/* Step to desired value, smoothly */
program[0] = PRESCALE_512 | STEPTIME_1 | incdec;
/* Loop eternally to 0x00 */
program[1] = BRANCH;
}
dev_dbg(chip->dev,
"PWM#%u: value = %02x, last_duty = %02x, program=%04x,%04x,%04x\n",
pwm->hwpwm, value, last, program[0], program[1],
program[2]);
stmpe_pwm->last_duty = value;
}
/*
* We can write programs of up to 64 16-bit words into this channel.
*/
for (i = 0; i < ARRAY_SIZE(program); i++) {
u8 value;
value = (program[i] >> 8) & 0xff;
ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
if (ret) {
dev_err(chip->dev, "error writing register %02x: %d\n",
offset, ret);
return ret;
}
value = program[i] & 0xff;
ret = stmpe_reg_write(stmpe_pwm->stmpe, offset, value);
if (ret) {
dev_err(chip->dev, "error writing register %02x: %d\n",
offset, ret);
return ret;
}
}
/* If we were enabled, re-enable this PWM */
if (pwm_is_enabled(pwm))
stmpe_24xx_pwm_enable(chip, pwm);
/* Sleep for 200ms so we're sure it will take effect */
msleep(200);
dev_dbg(chip->dev, "programmed PWM#%u, %u bytes\n", pwm->hwpwm, i);
return 0;
}
static int stmpe_24xx_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)
return stmpe_24xx_pwm_disable(chip, pwm);
return 0;
}
err = stmpe_24xx_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
if (err)
return err;
if (!pwm->state.enabled)
err = stmpe_24xx_pwm_enable(chip, pwm);
return err;
}
static const struct pwm_ops stmpe_24xx_pwm_ops = {
.apply = stmpe_24xx_pwm_apply,
.owner = THIS_MODULE,
};
static int __init stmpe_pwm_probe(struct platform_device *pdev)
{
struct stmpe *stmpe = dev_get_drvdata(pdev->dev.parent);
struct stmpe_pwm *stmpe_pwm;
int ret;
stmpe_pwm = devm_kzalloc(&pdev->dev, sizeof(*stmpe_pwm), GFP_KERNEL);
if (!stmpe_pwm)
return -ENOMEM;
stmpe_pwm->stmpe = stmpe;
stmpe_pwm->chip.dev = &pdev->dev;
if (stmpe->partnum == STMPE2401 || stmpe->partnum == STMPE2403) {
stmpe_pwm->chip.ops = &stmpe_24xx_pwm_ops;
stmpe_pwm->chip.npwm = 3;
} else {
if (stmpe->partnum == STMPE1601)
dev_err(&pdev->dev, "STMPE1601 not yet supported\n");
else
dev_err(&pdev->dev, "Unknown STMPE PWM\n");
return -ENODEV;
}
ret = stmpe_enable(stmpe, STMPE_BLOCK_PWM);
if (ret)
return ret;
ret = pwmchip_add(&stmpe_pwm->chip);
if (ret) {
stmpe_disable(stmpe, STMPE_BLOCK_PWM);
return ret;
}
return 0;
}
static struct platform_driver stmpe_pwm_driver = {
.driver = {
.name = "stmpe-pwm",
},
};
builtin_platform_driver_probe(stmpe_pwm_driver, stmpe_pwm_probe);
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