linux/drivers/pwm/pwm-imx27.c
Uwe Kleine-König e9fdf122cf pwm: Simplify all drivers with explicit of_pwm_n_cells = 3
With the previous commit there is no need for the lowlevel driver any
more to specify it it uses two or three cells. So simplify accordingly.

The only non-trival change affects the pwm-rockchip driver: It used to only
support three cells if the hardware supports polarity. Now the default
number depends on the device tree which has to match hardware anyhow
(and if it doesn't the error is just a bit delayed as a PWM handle with
an inverted setting is catched when pwm_apply_state() is called).

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2021-05-25 18:19:15 +02:00

369 lines
9.0 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* simple driver for PWM (Pulse Width Modulator) controller
*
* Derived from pxa PWM driver by eric miao <eric.miao@marvell.com>
*
* Limitations:
* - When disabled the output is driven to 0 independent of the configured
* polarity.
*/
#include <linux/bitfield.h>
#include <linux/bitops.h>
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/err.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/slab.h>
#define MX3_PWMCR 0x00 /* PWM Control Register */
#define MX3_PWMSR 0x04 /* PWM Status Register */
#define MX3_PWMSAR 0x0C /* PWM Sample Register */
#define MX3_PWMPR 0x10 /* PWM Period Register */
#define MX3_PWMCR_FWM GENMASK(27, 26)
#define MX3_PWMCR_STOPEN BIT(25)
#define MX3_PWMCR_DOZEN BIT(24)
#define MX3_PWMCR_WAITEN BIT(23)
#define MX3_PWMCR_DBGEN BIT(22)
#define MX3_PWMCR_BCTR BIT(21)
#define MX3_PWMCR_HCTR BIT(20)
#define MX3_PWMCR_POUTC GENMASK(19, 18)
#define MX3_PWMCR_POUTC_NORMAL 0
#define MX3_PWMCR_POUTC_INVERTED 1
#define MX3_PWMCR_POUTC_OFF 2
#define MX3_PWMCR_CLKSRC GENMASK(17, 16)
#define MX3_PWMCR_CLKSRC_OFF 0
#define MX3_PWMCR_CLKSRC_IPG 1
#define MX3_PWMCR_CLKSRC_IPG_HIGH 2
#define MX3_PWMCR_CLKSRC_IPG_32K 3
#define MX3_PWMCR_PRESCALER GENMASK(15, 4)
#define MX3_PWMCR_SWR BIT(3)
#define MX3_PWMCR_REPEAT GENMASK(2, 1)
#define MX3_PWMCR_REPEAT_1X 0
#define MX3_PWMCR_REPEAT_2X 1
#define MX3_PWMCR_REPEAT_4X 2
#define MX3_PWMCR_REPEAT_8X 3
#define MX3_PWMCR_EN BIT(0)
#define MX3_PWMSR_FWE BIT(6)
#define MX3_PWMSR_CMP BIT(5)
#define MX3_PWMSR_ROV BIT(4)
#define MX3_PWMSR_FE BIT(3)
#define MX3_PWMSR_FIFOAV GENMASK(2, 0)
#define MX3_PWMSR_FIFOAV_EMPTY 0
#define MX3_PWMSR_FIFOAV_1WORD 1
#define MX3_PWMSR_FIFOAV_2WORDS 2
#define MX3_PWMSR_FIFOAV_3WORDS 3
#define MX3_PWMSR_FIFOAV_4WORDS 4
#define MX3_PWMCR_PRESCALER_SET(x) FIELD_PREP(MX3_PWMCR_PRESCALER, (x) - 1)
#define MX3_PWMCR_PRESCALER_GET(x) (FIELD_GET(MX3_PWMCR_PRESCALER, \
(x)) + 1)
#define MX3_PWM_SWR_LOOP 5
/* PWMPR register value of 0xffff has the same effect as 0xfffe */
#define MX3_PWMPR_MAX 0xfffe
struct pwm_imx27_chip {
struct clk *clk_ipg;
struct clk *clk_per;
void __iomem *mmio_base;
struct pwm_chip chip;
/*
* The driver cannot read the current duty cycle from the hardware if
* the hardware is disabled. Cache the last programmed duty cycle
* value to return in that case.
*/
unsigned int duty_cycle;
};
#define to_pwm_imx27_chip(chip) container_of(chip, struct pwm_imx27_chip, chip)
static int pwm_imx27_clk_prepare_enable(struct pwm_imx27_chip *imx)
{
int ret;
ret = clk_prepare_enable(imx->clk_ipg);
if (ret)
return ret;
ret = clk_prepare_enable(imx->clk_per);
if (ret) {
clk_disable_unprepare(imx->clk_ipg);
return ret;
}
return 0;
}
static void pwm_imx27_clk_disable_unprepare(struct pwm_imx27_chip *imx)
{
clk_disable_unprepare(imx->clk_per);
clk_disable_unprepare(imx->clk_ipg);
}
static void pwm_imx27_get_state(struct pwm_chip *chip,
struct pwm_device *pwm, struct pwm_state *state)
{
struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
u32 period, prescaler, pwm_clk, val;
u64 tmp;
int ret;
ret = pwm_imx27_clk_prepare_enable(imx);
if (ret < 0)
return;
val = readl(imx->mmio_base + MX3_PWMCR);
if (val & MX3_PWMCR_EN)
state->enabled = true;
else
state->enabled = false;
switch (FIELD_GET(MX3_PWMCR_POUTC, val)) {
case MX3_PWMCR_POUTC_NORMAL:
state->polarity = PWM_POLARITY_NORMAL;
break;
case MX3_PWMCR_POUTC_INVERTED:
state->polarity = PWM_POLARITY_INVERSED;
break;
default:
dev_warn(chip->dev, "can't set polarity, output disconnected");
}
prescaler = MX3_PWMCR_PRESCALER_GET(val);
pwm_clk = clk_get_rate(imx->clk_per);
val = readl(imx->mmio_base + MX3_PWMPR);
period = val >= MX3_PWMPR_MAX ? MX3_PWMPR_MAX : val;
/* PWMOUT (Hz) = PWMCLK / (PWMPR + 2) */
tmp = NSEC_PER_SEC * (u64)(period + 2) * prescaler;
state->period = DIV_ROUND_UP_ULL(tmp, pwm_clk);
/*
* PWMSAR can be read only if PWM is enabled. If the PWM is disabled,
* use the cached value.
*/
if (state->enabled)
val = readl(imx->mmio_base + MX3_PWMSAR);
else
val = imx->duty_cycle;
tmp = NSEC_PER_SEC * (u64)(val) * prescaler;
state->duty_cycle = DIV_ROUND_UP_ULL(tmp, pwm_clk);
pwm_imx27_clk_disable_unprepare(imx);
}
static void pwm_imx27_sw_reset(struct pwm_chip *chip)
{
struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
struct device *dev = chip->dev;
int wait_count = 0;
u32 cr;
writel(MX3_PWMCR_SWR, imx->mmio_base + MX3_PWMCR);
do {
usleep_range(200, 1000);
cr = readl(imx->mmio_base + MX3_PWMCR);
} while ((cr & MX3_PWMCR_SWR) &&
(wait_count++ < MX3_PWM_SWR_LOOP));
if (cr & MX3_PWMCR_SWR)
dev_warn(dev, "software reset timeout\n");
}
static void pwm_imx27_wait_fifo_slot(struct pwm_chip *chip,
struct pwm_device *pwm)
{
struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
struct device *dev = chip->dev;
unsigned int period_ms;
int fifoav;
u32 sr;
sr = readl(imx->mmio_base + MX3_PWMSR);
fifoav = FIELD_GET(MX3_PWMSR_FIFOAV, sr);
if (fifoav == MX3_PWMSR_FIFOAV_4WORDS) {
period_ms = DIV_ROUND_UP_ULL(pwm_get_period(pwm),
NSEC_PER_MSEC);
msleep(period_ms);
sr = readl(imx->mmio_base + MX3_PWMSR);
if (fifoav == FIELD_GET(MX3_PWMSR_FIFOAV, sr))
dev_warn(dev, "there is no free FIFO slot\n");
}
}
static int pwm_imx27_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
unsigned long period_cycles, duty_cycles, prescale;
struct pwm_imx27_chip *imx = to_pwm_imx27_chip(chip);
struct pwm_state cstate;
unsigned long long c;
unsigned long long clkrate;
int ret;
u32 cr;
pwm_get_state(pwm, &cstate);
clkrate = clk_get_rate(imx->clk_per);
c = clkrate * state->period;
do_div(c, NSEC_PER_SEC);
period_cycles = c;
prescale = period_cycles / 0x10000 + 1;
period_cycles /= prescale;
c = clkrate * state->duty_cycle;
do_div(c, NSEC_PER_SEC);
duty_cycles = c;
duty_cycles /= prescale;
/*
* according to imx pwm RM, the real period value should be PERIOD
* value in PWMPR plus 2.
*/
if (period_cycles > 2)
period_cycles -= 2;
else
period_cycles = 0;
/*
* Wait for a free FIFO slot if the PWM is already enabled, and flush
* the FIFO if the PWM was disabled and is about to be enabled.
*/
if (cstate.enabled) {
pwm_imx27_wait_fifo_slot(chip, pwm);
} else {
ret = pwm_imx27_clk_prepare_enable(imx);
if (ret)
return ret;
pwm_imx27_sw_reset(chip);
}
writel(duty_cycles, imx->mmio_base + MX3_PWMSAR);
writel(period_cycles, imx->mmio_base + MX3_PWMPR);
/*
* Store the duty cycle for future reference in cases where the
* MX3_PWMSAR register can't be read (i.e. when the PWM is disabled).
*/
imx->duty_cycle = duty_cycles;
cr = MX3_PWMCR_PRESCALER_SET(prescale) |
MX3_PWMCR_STOPEN | MX3_PWMCR_DOZEN | MX3_PWMCR_WAITEN |
FIELD_PREP(MX3_PWMCR_CLKSRC, MX3_PWMCR_CLKSRC_IPG_HIGH) |
MX3_PWMCR_DBGEN;
if (state->polarity == PWM_POLARITY_INVERSED)
cr |= FIELD_PREP(MX3_PWMCR_POUTC,
MX3_PWMCR_POUTC_INVERTED);
if (state->enabled)
cr |= MX3_PWMCR_EN;
writel(cr, imx->mmio_base + MX3_PWMCR);
if (!state->enabled)
pwm_imx27_clk_disable_unprepare(imx);
return 0;
}
static const struct pwm_ops pwm_imx27_ops = {
.apply = pwm_imx27_apply,
.get_state = pwm_imx27_get_state,
.owner = THIS_MODULE,
};
static const struct of_device_id pwm_imx27_dt_ids[] = {
{ .compatible = "fsl,imx27-pwm", },
{ /* sentinel */ }
};
MODULE_DEVICE_TABLE(of, pwm_imx27_dt_ids);
static int pwm_imx27_probe(struct platform_device *pdev)
{
struct pwm_imx27_chip *imx;
int ret;
u32 pwmcr;
imx = devm_kzalloc(&pdev->dev, sizeof(*imx), GFP_KERNEL);
if (imx == NULL)
return -ENOMEM;
platform_set_drvdata(pdev, imx);
imx->clk_ipg = devm_clk_get(&pdev->dev, "ipg");
if (IS_ERR(imx->clk_ipg))
return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_ipg),
"getting ipg clock failed\n");
imx->clk_per = devm_clk_get(&pdev->dev, "per");
if (IS_ERR(imx->clk_per))
return dev_err_probe(&pdev->dev, PTR_ERR(imx->clk_per),
"failed to get peripheral clock\n");
imx->chip.ops = &pwm_imx27_ops;
imx->chip.dev = &pdev->dev;
imx->chip.npwm = 1;
imx->mmio_base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(imx->mmio_base))
return PTR_ERR(imx->mmio_base);
ret = pwm_imx27_clk_prepare_enable(imx);
if (ret)
return ret;
/* keep clks on if pwm is running */
pwmcr = readl(imx->mmio_base + MX3_PWMCR);
if (!(pwmcr & MX3_PWMCR_EN))
pwm_imx27_clk_disable_unprepare(imx);
return pwmchip_add(&imx->chip);
}
static int pwm_imx27_remove(struct platform_device *pdev)
{
struct pwm_imx27_chip *imx;
imx = platform_get_drvdata(pdev);
return pwmchip_remove(&imx->chip);
}
static struct platform_driver imx_pwm_driver = {
.driver = {
.name = "pwm-imx27",
.of_match_table = pwm_imx27_dt_ids,
},
.probe = pwm_imx27_probe,
.remove = pwm_imx27_remove,
};
module_platform_driver(imx_pwm_driver);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Sascha Hauer <s.hauer@pengutronix.de>");