linux/drivers/pwm/pwm-tegra.c
Uwe Kleine-König 384461abca pwm: Manage owner assignment implicitly for drivers
Instead of requiring each driver to care for assigning the owner member
of struct pwm_ops, handle that implicitly using a macro. Note that the
owner member has to be moved to struct pwm_chip, as the ops structure
usually lives in read-only memory and so cannot be modified.

The upside is that new low level drivers cannot forget the assignment and
save one line each. The pwm-crc driver didn't assign .owner, that's not
a problem in practice though as the driver cannot be compiled as a
module.

Acked-by: Andy Shevchenko <andy.shevchenko@gmail.com> # Intel LPSS
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com> # pwm-{bcm,brcm}*.c
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com> # sun4i
Acked-by: Andi Shyti <andi.shyti@kernel.org>
Acked-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp> # pwm-visconti
Acked-by: Heiko Stuebner <heiko@sntech.de> # pwm-rockchip
Acked-by: Michael Walle <michael@walle.cc> # pwm-sl28cpld
Acked-by: Neil Armstrong <neil.armstrong@linaro.org> # pwm-meson
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Link: https://lore.kernel.org/r/20230804142707.412137-2-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>
2023-10-13 10:07:17 +02:00

442 lines
11 KiB
C
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

// SPDX-License-Identifier: GPL-2.0-or-later
/*
* drivers/pwm/pwm-tegra.c
*
* Tegra pulse-width-modulation controller driver
*
* Copyright (c) 2010-2020, NVIDIA Corporation.
* Based on arch/arm/plat-mxc/pwm.c by Sascha Hauer <s.hauer@pengutronix.de>
*
* Overview of Tegra Pulse Width Modulator Register:
* 1. 13-bit: Frequency division (SCALE)
* 2. 8-bit : Pulse division (DUTY)
* 3. 1-bit : Enable bit
*
* The PWM clock frequency is divided by 256 before subdividing it based
* on the programmable frequency division value to generate the required
* frequency for PWM output. The maximum output frequency that can be
* achieved is (max rate of source clock) / 256.
* e.g. if source clock rate is 408 MHz, maximum output frequency can be:
* 408 MHz/256 = 1.6 MHz.
* This 1.6 MHz frequency can further be divided using SCALE value in PWM.
*
* PWM pulse width: 8 bits are usable [23:16] for varying pulse width.
* To achieve 100% duty cycle, program Bit [24] of this register to
* 1b1. In which case the other bits [23:16] are set to don't care.
*
* Limitations:
* - When PWM is disabled, the output is driven to inactive.
* - It does not allow the current PWM period to complete and
* stops abruptly.
*
* - If the register is reconfigured while PWM is running,
* it does not complete the currently running period.
*
* - If the user input duty is beyond acceptible limits,
* -EINVAL is returned.
*/
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/pm_opp.h>
#include <linux/pwm.h>
#include <linux/platform_device.h>
#include <linux/pinctrl/consumer.h>
#include <linux/pm_runtime.h>
#include <linux/slab.h>
#include <linux/reset.h>
#include <soc/tegra/common.h>
#define PWM_ENABLE (1 << 31)
#define PWM_DUTY_WIDTH 8
#define PWM_DUTY_SHIFT 16
#define PWM_SCALE_WIDTH 13
#define PWM_SCALE_SHIFT 0
struct tegra_pwm_soc {
unsigned int num_channels;
/* Maximum IP frequency for given SoCs */
unsigned long max_frequency;
};
struct tegra_pwm_chip {
struct pwm_chip chip;
struct device *dev;
struct clk *clk;
struct reset_control*rst;
unsigned long clk_rate;
unsigned long min_period_ns;
void __iomem *regs;
const struct tegra_pwm_soc *soc;
};
static inline struct tegra_pwm_chip *to_tegra_pwm_chip(struct pwm_chip *chip)
{
return container_of(chip, struct tegra_pwm_chip, chip);
}
static inline u32 pwm_readl(struct tegra_pwm_chip *pc, unsigned int offset)
{
return readl(pc->regs + (offset << 4));
}
static inline void pwm_writel(struct tegra_pwm_chip *pc, unsigned int offset, u32 value)
{
writel(value, pc->regs + (offset << 4));
}
static int tegra_pwm_config(struct pwm_chip *chip, struct pwm_device *pwm,
int duty_ns, int period_ns)
{
struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
unsigned long long c = duty_ns;
unsigned long rate, required_clk_rate;
u32 val = 0;
int err;
/*
* Convert from duty_ns / period_ns to a fixed number of duty ticks
* per (1 << PWM_DUTY_WIDTH) cycles and make sure to round to the
* nearest integer during division.
*/
c *= (1 << PWM_DUTY_WIDTH);
c = DIV_ROUND_CLOSEST_ULL(c, period_ns);
val = (u32)c << PWM_DUTY_SHIFT;
/*
* min period = max clock limit >> PWM_DUTY_WIDTH
*/
if (period_ns < pc->min_period_ns)
return -EINVAL;
/*
* Compute the prescaler value for which (1 << PWM_DUTY_WIDTH)
* cycles at the PWM clock rate will take period_ns nanoseconds.
*
* num_channels: If single instance of PWM controller has multiple
* channels (e.g. Tegra210 or older) then it is not possible to
* configure separate clock rates to each of the channels, in such
* case the value stored during probe will be referred.
*
* If every PWM controller instance has one channel respectively, i.e.
* nums_channels == 1 then only the clock rate can be modified
* dynamically (e.g. Tegra186 or Tegra194).
*/
if (pc->soc->num_channels == 1) {
/*
* Rate is multiplied with 2^PWM_DUTY_WIDTH so that it matches
* with the maximum possible rate that the controller can
* provide. Any further lower value can be derived by setting
* PFM bits[0:12].
*
* required_clk_rate is a reference rate for source clock and
* it is derived based on user requested period. By setting the
* source clock rate as required_clk_rate, PWM controller will
* be able to configure the requested period.
*/
required_clk_rate = DIV_ROUND_UP_ULL((u64)NSEC_PER_SEC << PWM_DUTY_WIDTH,
period_ns);
if (required_clk_rate > clk_round_rate(pc->clk, required_clk_rate))
/*
* required_clk_rate is a lower bound for the input
* rate; for lower rates there is no value for PWM_SCALE
* that yields a period less than or equal to the
* requested period. Hence, for lower rates, double the
* required_clk_rate to get a clock rate that can meet
* the requested period.
*/
required_clk_rate *= 2;
err = dev_pm_opp_set_rate(pc->dev, required_clk_rate);
if (err < 0)
return -EINVAL;
/* Store the new rate for further references */
pc->clk_rate = clk_get_rate(pc->clk);
}
/* Consider precision in PWM_SCALE_WIDTH rate calculation */
rate = mul_u64_u64_div_u64(pc->clk_rate, period_ns,
(u64)NSEC_PER_SEC << PWM_DUTY_WIDTH);
/*
* Since the actual PWM divider is the register's frequency divider
* field plus 1, we need to decrement to get the correct value to
* write to the register.
*/
if (rate > 0)
rate--;
else
return -EINVAL;
/*
* Make sure that the rate will fit in the register's frequency
* divider field.
*/
if (rate >> PWM_SCALE_WIDTH)
return -EINVAL;
val |= rate << PWM_SCALE_SHIFT;
/*
* If the PWM channel is disabled, make sure to turn on the clock
* before writing the register. Otherwise, keep it enabled.
*/
if (!pwm_is_enabled(pwm)) {
err = pm_runtime_resume_and_get(pc->dev);
if (err)
return err;
} else
val |= PWM_ENABLE;
pwm_writel(pc, pwm->hwpwm, val);
/*
* If the PWM is not enabled, turn the clock off again to save power.
*/
if (!pwm_is_enabled(pwm))
pm_runtime_put(pc->dev);
return 0;
}
static int tegra_pwm_enable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
int rc = 0;
u32 val;
rc = pm_runtime_resume_and_get(pc->dev);
if (rc)
return rc;
val = pwm_readl(pc, pwm->hwpwm);
val |= PWM_ENABLE;
pwm_writel(pc, pwm->hwpwm, val);
return 0;
}
static void tegra_pwm_disable(struct pwm_chip *chip, struct pwm_device *pwm)
{
struct tegra_pwm_chip *pc = to_tegra_pwm_chip(chip);
u32 val;
val = pwm_readl(pc, pwm->hwpwm);
val &= ~PWM_ENABLE;
pwm_writel(pc, pwm->hwpwm, val);
pm_runtime_put_sync(pc->dev);
}
static int tegra_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
const struct pwm_state *state)
{
int err;
bool enabled = pwm->state.enabled;
if (state->polarity != PWM_POLARITY_NORMAL)
return -EINVAL;
if (!state->enabled) {
if (enabled)
tegra_pwm_disable(chip, pwm);
return 0;
}
err = tegra_pwm_config(pwm->chip, pwm, state->duty_cycle, state->period);
if (err)
return err;
if (!enabled)
err = tegra_pwm_enable(chip, pwm);
return err;
}
static const struct pwm_ops tegra_pwm_ops = {
.apply = tegra_pwm_apply,
};
static int tegra_pwm_probe(struct platform_device *pdev)
{
struct tegra_pwm_chip *pc;
int ret;
pc = devm_kzalloc(&pdev->dev, sizeof(*pc), GFP_KERNEL);
if (!pc)
return -ENOMEM;
pc->soc = of_device_get_match_data(&pdev->dev);
pc->dev = &pdev->dev;
pc->regs = devm_platform_ioremap_resource(pdev, 0);
if (IS_ERR(pc->regs))
return PTR_ERR(pc->regs);
platform_set_drvdata(pdev, pc);
pc->clk = devm_clk_get(&pdev->dev, NULL);
if (IS_ERR(pc->clk))
return PTR_ERR(pc->clk);
ret = devm_tegra_core_dev_init_opp_table_common(&pdev->dev);
if (ret)
return ret;
pm_runtime_enable(&pdev->dev);
ret = pm_runtime_resume_and_get(&pdev->dev);
if (ret)
return ret;
/* Set maximum frequency of the IP */
ret = dev_pm_opp_set_rate(pc->dev, pc->soc->max_frequency);
if (ret < 0) {
dev_err(&pdev->dev, "Failed to set max frequency: %d\n", ret);
goto put_pm;
}
/*
* The requested and configured frequency may differ due to
* clock register resolutions. Get the configured frequency
* so that PWM period can be calculated more accurately.
*/
pc->clk_rate = clk_get_rate(pc->clk);
/* Set minimum limit of PWM period for the IP */
pc->min_period_ns =
(NSEC_PER_SEC / (pc->soc->max_frequency >> PWM_DUTY_WIDTH)) + 1;
pc->rst = devm_reset_control_get_exclusive(&pdev->dev, "pwm");
if (IS_ERR(pc->rst)) {
ret = PTR_ERR(pc->rst);
dev_err(&pdev->dev, "Reset control is not found: %d\n", ret);
goto put_pm;
}
reset_control_deassert(pc->rst);
pc->chip.dev = &pdev->dev;
pc->chip.ops = &tegra_pwm_ops;
pc->chip.npwm = pc->soc->num_channels;
ret = pwmchip_add(&pc->chip);
if (ret < 0) {
dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
reset_control_assert(pc->rst);
goto put_pm;
}
pm_runtime_put(&pdev->dev);
return 0;
put_pm:
pm_runtime_put_sync_suspend(&pdev->dev);
pm_runtime_force_suspend(&pdev->dev);
return ret;
}
static void tegra_pwm_remove(struct platform_device *pdev)
{
struct tegra_pwm_chip *pc = platform_get_drvdata(pdev);
pwmchip_remove(&pc->chip);
reset_control_assert(pc->rst);
pm_runtime_force_suspend(&pdev->dev);
}
static int __maybe_unused tegra_pwm_runtime_suspend(struct device *dev)
{
struct tegra_pwm_chip *pc = dev_get_drvdata(dev);
int err;
clk_disable_unprepare(pc->clk);
err = pinctrl_pm_select_sleep_state(dev);
if (err) {
clk_prepare_enable(pc->clk);
return err;
}
return 0;
}
static int __maybe_unused tegra_pwm_runtime_resume(struct device *dev)
{
struct tegra_pwm_chip *pc = dev_get_drvdata(dev);
int err;
err = pinctrl_pm_select_default_state(dev);
if (err)
return err;
err = clk_prepare_enable(pc->clk);
if (err) {
pinctrl_pm_select_sleep_state(dev);
return err;
}
return 0;
}
static const struct tegra_pwm_soc tegra20_pwm_soc = {
.num_channels = 4,
.max_frequency = 48000000UL,
};
static const struct tegra_pwm_soc tegra186_pwm_soc = {
.num_channels = 1,
.max_frequency = 102000000UL,
};
static const struct tegra_pwm_soc tegra194_pwm_soc = {
.num_channels = 1,
.max_frequency = 408000000UL,
};
static const struct of_device_id tegra_pwm_of_match[] = {
{ .compatible = "nvidia,tegra20-pwm", .data = &tegra20_pwm_soc },
{ .compatible = "nvidia,tegra186-pwm", .data = &tegra186_pwm_soc },
{ .compatible = "nvidia,tegra194-pwm", .data = &tegra194_pwm_soc },
{ }
};
MODULE_DEVICE_TABLE(of, tegra_pwm_of_match);
static const struct dev_pm_ops tegra_pwm_pm_ops = {
SET_RUNTIME_PM_OPS(tegra_pwm_runtime_suspend, tegra_pwm_runtime_resume,
NULL)
SET_SYSTEM_SLEEP_PM_OPS(pm_runtime_force_suspend,
pm_runtime_force_resume)
};
static struct platform_driver tegra_pwm_driver = {
.driver = {
.name = "tegra-pwm",
.of_match_table = tegra_pwm_of_match,
.pm = &tegra_pwm_pm_ops,
},
.probe = tegra_pwm_probe,
.remove_new = tegra_pwm_remove,
};
module_platform_driver(tegra_pwm_driver);
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Sandipan Patra <spatra@nvidia.com>");
MODULE_DESCRIPTION("Tegra PWM controller driver");
MODULE_ALIAS("platform:tegra-pwm");