linux/drivers/pwm/pwm-visconti.c
Uwe Kleine-König 6c452cff79 pwm: Make .get_state() callback return an error code
.get_state() might fail in some cases. To make it possible that a driver
signals such a failure change the prototype of .get_state() to return an
error code.

This patch was created using coccinelle and the following semantic patch:

@p1@
identifier getstatefunc;
identifier driver;
@@
 struct pwm_ops driver = {
        ...,
        .get_state = getstatefunc
        ,...
 };

@p2@
identifier p1.getstatefunc;
identifier chip, pwm, state;
@@
-void
+int
 getstatefunc(struct pwm_chip *chip, struct pwm_device *pwm, struct pwm_state *state)
 {
   ...
-  return;
+  return 0;
   ...
 }

plus the actual change of the prototype in include/linux/pwm.h (plus some
manual fixing of indentions and empty lines).

So for now all drivers return success unconditionally. They are adapted
in the following patches to make the changes easier reviewable.

Reviewed-by: Heiko Stuebner <heiko@sntech.de>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Reviewed-by: Neil Armstrong <neil.armstrong@linaro.org>
Reviewed-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Reviewed-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
Acked-by: Douglas Anderson <dianders@chromium.org>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Acked-by: Pavel Machek <pavel@ucw.cz>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
Link: https://lore.kernel.org/r/20221130152148.2769768-2-u.kleine-koenig@pengutronix.de
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thierry Reding <thierry.reding@gmail.com>
2022-12-06 12:46:22 +01:00

178 lines
4.8 KiB
C

// SPDX-License-Identifier: GPL-2.0-only
/*
* Toshiba Visconti pulse-width-modulation controller driver
*
* Copyright (c) 2020 - 2021 TOSHIBA CORPORATION
* Copyright (c) 2020 - 2021 Toshiba Electronic Devices & Storage Corporation
*
* Authors: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
*
* Limitations:
* - The fixed input clock is running at 1 MHz and is divided by either 1,
* 2, 4 or 8.
* - When the settings of the PWM are modified, the new values are shadowed
* in hardware until the PIPGM_PCSR register is written and the currently
* running period is completed. This way the hardware switches atomically
* from the old setting to the new.
* - Disabling the hardware completes the currently running period and keeps
* the output at low level at all times.
*/
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/pwm.h>
#define PIPGM_PCSR(ch) (0x400 + 4 * (ch))
#define PIPGM_PDUT(ch) (0x420 + 4 * (ch))
#define PIPGM_PWMC(ch) (0x440 + 4 * (ch))
#define PIPGM_PWMC_PWMACT BIT(5)
#define PIPGM_PWMC_CLK_MASK GENMASK(1, 0)
#define PIPGM_PWMC_POLARITY_MASK GENMASK(5, 5)
struct visconti_pwm_chip {
struct pwm_chip chip;
void __iomem *base;
};
static inline struct visconti_pwm_chip *visconti_pwm_from_chip(struct pwm_chip *chip)
{
return container_of(chip, struct visconti_pwm_chip, chip);
}
static int visconti_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
u32 period, duty_cycle, pwmc0;
if (!state->enabled) {
writel(0, priv->base + PIPGM_PCSR(pwm->hwpwm));
return 0;
}
/*
* The biggest period the hardware can provide is
* (0xffff << 3) * 1000 ns
* This value fits easily in an u32, so simplify the maths by
* capping the values to 32 bit integers.
*/
if (state->period > (0xffff << 3) * 1000)
period = (0xffff << 3) * 1000;
else
period = state->period;
if (state->duty_cycle > period)
duty_cycle = period;
else
duty_cycle = state->duty_cycle;
/*
* The input clock runs fixed at 1 MHz, so we have only
* microsecond resolution and so can divide by
* NSEC_PER_SEC / CLKFREQ = 1000 without losing precision.
*/
period /= 1000;
duty_cycle /= 1000;
if (!period)
return -ERANGE;
/*
* PWMC controls a divider that divides the input clk by a power of two
* between 1 and 8. As a smaller divider yields higher precision, pick
* the smallest possible one. As period is at most 0xffff << 3, pwmc0 is
* in the intended range [0..3].
*/
pwmc0 = fls(period >> 16);
if (WARN_ON(pwmc0 > 3))
return -EINVAL;
period >>= pwmc0;
duty_cycle >>= pwmc0;
if (state->polarity == PWM_POLARITY_INVERSED)
pwmc0 |= PIPGM_PWMC_PWMACT;
writel(pwmc0, priv->base + PIPGM_PWMC(pwm->hwpwm));
writel(duty_cycle, priv->base + PIPGM_PDUT(pwm->hwpwm));
writel(period, priv->base + PIPGM_PCSR(pwm->hwpwm));
return 0;
}
static int visconti_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
struct pwm_state *state)
{
struct visconti_pwm_chip *priv = visconti_pwm_from_chip(chip);
u32 period, duty, pwmc0, pwmc0_clk;
period = readl(priv->base + PIPGM_PCSR(pwm->hwpwm));
duty = readl(priv->base + PIPGM_PDUT(pwm->hwpwm));
pwmc0 = readl(priv->base + PIPGM_PWMC(pwm->hwpwm));
pwmc0_clk = pwmc0 & PIPGM_PWMC_CLK_MASK;
state->period = (period << pwmc0_clk) * NSEC_PER_USEC;
state->duty_cycle = (duty << pwmc0_clk) * NSEC_PER_USEC;
if (pwmc0 & PIPGM_PWMC_POLARITY_MASK)
state->polarity = PWM_POLARITY_INVERSED;
else
state->polarity = PWM_POLARITY_NORMAL;
state->enabled = true;
return 0;
}
static const struct pwm_ops visconti_pwm_ops = {
.apply = visconti_pwm_apply,
.get_state = visconti_pwm_get_state,
.owner = THIS_MODULE,
};
static int visconti_pwm_probe(struct platform_device *pdev)
{
struct device *dev = &pdev->dev;
struct visconti_pwm_chip *priv;
int ret;
priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
if (!priv)
return -ENOMEM;
priv->base = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(priv->base))
return PTR_ERR(priv->base);
priv->chip.dev = dev;
priv->chip.ops = &visconti_pwm_ops;
priv->chip.npwm = 4;
ret = devm_pwmchip_add(&pdev->dev, &priv->chip);
if (ret < 0)
return dev_err_probe(&pdev->dev, ret, "Cannot register visconti PWM\n");
return 0;
}
static const struct of_device_id visconti_pwm_of_match[] = {
{ .compatible = "toshiba,visconti-pwm", },
{ }
};
MODULE_DEVICE_TABLE(of, visconti_pwm_of_match);
static struct platform_driver visconti_pwm_driver = {
.driver = {
.name = "pwm-visconti",
.of_match_table = visconti_pwm_of_match,
},
.probe = visconti_pwm_probe,
};
module_platform_driver(visconti_pwm_driver);
MODULE_LICENSE("GPL v2");
MODULE_AUTHOR("Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>");
MODULE_ALIAS("platform:pwm-visconti");