lkml.org 
[lkml]   [2020]   [Jul]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH v5 07/13] pwm: add support for sl28cpld PWM controller
    Date
    Add support for the PWM controller of the sl28cpld board management
    controller. This is part of a multi-function device driver.

    The controller has one PWM channel and can just generate four distinct
    frequencies.

    Signed-off-by: Michael Walle <michael@walle.cc>
    ---
    Changes since v4:
    - update copyright year
    - remove #include <linux/of_device.h>, suggested by Andy.
    - make the pwm mode table look nicer, suggested by Lee.
    - use dev_get_drvdata(chip->dev) instead of container_of(), suggested by
    Lee.
    - use whole sentence in comments, suggested by Lee.
    - renamed the local "struct sl28cpld_pwm" variable to "priv" everywhere,
    suggested by Lee.
    - use pwm_{get,set}_relative_duty_cycle(), suggested by Andy.
    - make the comment about the 250Hz hardware limitation clearer
    - don't use "if (ret < 0)", but only "if (ret)", suggested by Andy.
    - don't use KBUID_MODNAME
    - remove comma in terminator line of the compatible strings list
    - remove the platform device table

    Changes since v3:
    - see cover letter

    drivers/pwm/Kconfig | 10 ++
    drivers/pwm/Makefile | 1 +
    drivers/pwm/pwm-sl28cpld.c | 187 +++++++++++++++++++++++++++++++++++++
    3 files changed, 198 insertions(+)
    create mode 100644 drivers/pwm/pwm-sl28cpld.c

    diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
    index 7dbcf6973d33..a0d50d70c3b9 100644
    --- a/drivers/pwm/Kconfig
    +++ b/drivers/pwm/Kconfig
    @@ -428,6 +428,16 @@ config PWM_SIFIVE
    To compile this driver as a module, choose M here: the module
    will be called pwm-sifive.

    +config PWM_SL28CPLD
    + tristate "Kontron sl28cpld PWM support"
    + select MFD_SIMPLE_MFD_I2C
    + help
    + Generic PWM framework driver for board management controller
    + found on the Kontron sl28 CPLD.
    +
    + To compile this driver as a module, choose M here: the module
    + will be called pwm-sl28cpld.
    +
    config PWM_SPEAR
    tristate "STMicroelectronics SPEAr PWM support"
    depends on PLAT_SPEAR || COMPILE_TEST
    diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
    index 2c2ba0a03557..cbdcd55d69ee 100644
    --- a/drivers/pwm/Makefile
    +++ b/drivers/pwm/Makefile
    @@ -40,6 +40,7 @@ obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o
    obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o
    obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
    obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o
    +obj-$(CONFIG_PWM_SL28CPLD) += pwm-sl28cpld.o
    obj-$(CONFIG_PWM_SPEAR) += pwm-spear.o
    obj-$(CONFIG_PWM_SPRD) += pwm-sprd.o
    obj-$(CONFIG_PWM_STI) += pwm-sti.o
    diff --git a/drivers/pwm/pwm-sl28cpld.c b/drivers/pwm/pwm-sl28cpld.c
    new file mode 100644
    index 000000000000..8ee286b605bf
    --- /dev/null
    +++ b/drivers/pwm/pwm-sl28cpld.c
    @@ -0,0 +1,187 @@
    +// SPDX-License-Identifier: GPL-2.0-only
    +/*
    + * sl28cpld PWM driver
    + *
    + * Copyright 2020 Kontron Europe GmbH
    + */
    +
    +#include <linux/bitfield.h>
    +#include <linux/kernel.h>
    +#include <linux/mod_devicetable.h>
    +#include <linux/module.h>
    +#include <linux/platform_device.h>
    +#include <linux/pwm.h>
    +#include <linux/regmap.h>
    +
    +/*
    + * PWM timer block registers.
    + */
    +#define PWM_CTRL 0x00
    +#define PWM_ENABLE BIT(7)
    +#define PWM_MODE_250HZ 0
    +#define PWM_MODE_500HZ 1
    +#define PWM_MODE_1KHZ 2
    +#define PWM_MODE_2KHZ 3
    +#define PWM_MODE_MASK GENMASK(1, 0)
    +#define PWM_CYCLE 0x01
    +#define PWM_CYCLE_MAX 0x7f
    +
    +struct sl28cpld_pwm {
    + struct pwm_chip pwm_chip;
    + struct regmap *regmap;
    + u32 offset;
    +};
    +
    +struct sl28cpld_pwm_periods {
    + u8 ctrl;
    + unsigned long duty_cycle;
    +};
    +
    +struct sl28cpld_pwm_config {
    + unsigned long period_ns;
    + u8 max_duty_cycle;
    +};
    +
    +static struct sl28cpld_pwm_config sl28cpld_pwm_config[] = {
    + [PWM_MODE_250HZ] = { .period_ns = 4000000, .max_duty_cycle = 0x80 },
    + [PWM_MODE_500HZ] = { .period_ns = 2000000, .max_duty_cycle = 0x40 },
    + [PWM_MODE_1KHZ] = { .period_ns = 1000000, .max_duty_cycle = 0x20 },
    + [PWM_MODE_2KHZ] = { .period_ns = 500000, .max_duty_cycle = 0x10 },
    +};
    +
    +static void sl28cpld_pwm_get_state(struct pwm_chip *chip,
    + struct pwm_device *pwm,
    + struct pwm_state *state)
    +{
    + struct sl28cpld_pwm *priv = dev_get_drvdata(chip->dev);
    + static struct sl28cpld_pwm_config *config;
    + unsigned int reg;
    + unsigned int mode;
    +
    + regmap_read(priv->regmap, priv->offset + PWM_CTRL, &reg);
    +
    + state->enabled = reg & PWM_ENABLE;
    +
    + mode = FIELD_GET(PWM_MODE_MASK, reg);
    + config = &sl28cpld_pwm_config[mode];
    + state->period = config->period_ns;
    +
    + regmap_read(priv->regmap, priv->offset + PWM_CYCLE, &reg);
    + pwm_set_relative_duty_cycle(state, reg, config->max_duty_cycle);
    +}
    +
    +static int sl28cpld_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
    + const struct pwm_state *state)
    +{
    + struct sl28cpld_pwm *priv = dev_get_drvdata(chip->dev);
    + struct sl28cpld_pwm_config *config;
    + unsigned int cycle;
    + int ret;
    + int mode;
    + u8 ctrl;
    +
    + /* Get the configuration by comparing the period */
    + for (mode = 0; mode < ARRAY_SIZE(sl28cpld_pwm_config); mode++) {
    + config = &sl28cpld_pwm_config[mode];
    + if (state->period == config->period_ns)
    + break;
    + }
    +
    + if (mode == ARRAY_SIZE(sl28cpld_pwm_config))
    + return -EINVAL;
    +
    + ctrl = FIELD_PREP(PWM_MODE_MASK, mode);
    + if (state->enabled)
    + ctrl |= PWM_ENABLE;
    +
    + cycle = pwm_get_relative_duty_cycle(state, config->max_duty_cycle);
    +
    + /*
    + * The hardware doesn't allow to set max_duty_cycle if the
    + * 250Hz mode is enabled, thus we have to trap that here.
    + * But because a 100% duty cycle is equal on all modes, i.e.
    + * it is just a "all-high" output, we trap any case with a
    + * 100% duty cycle and use the 500Hz mode.
    + */
    + if (cycle == config->max_duty_cycle) {
    + ctrl &= ~PWM_MODE_MASK;
    + ctrl |= FIELD_PREP(PWM_MODE_MASK, PWM_MODE_500HZ);
    + cycle = PWM_CYCLE_MAX;
    + }
    +
    + ret = regmap_write(priv->regmap, priv->offset + PWM_CTRL, ctrl);
    + if (ret)
    + return ret;
    +
    + return regmap_write(priv->regmap, priv->offset + PWM_CYCLE, (u8)cycle);
    +}
    +
    +static const struct pwm_ops sl28cpld_pwm_ops = {
    + .apply = sl28cpld_pwm_apply,
    + .get_state = sl28cpld_pwm_get_state,
    + .owner = THIS_MODULE,
    +};
    +
    +static int sl28cpld_pwm_probe(struct platform_device *pdev)
    +{
    + struct sl28cpld_pwm *priv;
    + struct pwm_chip *chip;
    + int ret;
    +
    + if (!pdev->dev.parent)
    + return -ENODEV;
    +
    + priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
    + if (!priv)
    + return -ENOMEM;
    +
    + priv->regmap = dev_get_regmap(pdev->dev.parent, NULL);
    + if (!priv->regmap)
    + return -ENODEV;
    +
    + ret = device_property_read_u32(&pdev->dev, "reg", &priv->offset);
    + if (ret)
    + return -EINVAL;
    +
    + /* Initialize the pwm_chip structure */
    + chip = &priv->pwm_chip;
    + chip->dev = &pdev->dev;
    + chip->ops = &sl28cpld_pwm_ops;
    + chip->base = -1;
    + chip->npwm = 1;
    +
    + ret = pwmchip_add(&priv->pwm_chip);
    + if (ret)
    + return ret;
    +
    + platform_set_drvdata(pdev, priv);
    +
    + return 0;
    +}
    +
    +static int sl28cpld_pwm_remove(struct platform_device *pdev)
    +{
    + struct sl28cpld_pwm *priv = platform_get_drvdata(pdev);
    +
    + return pwmchip_remove(&priv->pwm_chip);
    +}
    +
    +static const struct of_device_id sl28cpld_pwm_of_match[] = {
    + { .compatible = "kontron,sl28cpld-pwm" },
    + {}
    +};
    +MODULE_DEVICE_TABLE(of, sl28cpld_pwm_of_match);
    +
    +static struct platform_driver sl28cpld_pwm_driver = {
    + .probe = sl28cpld_pwm_probe,
    + .remove = sl28cpld_pwm_remove,
    + .driver = {
    + .name = "sl28cpld-pwm",
    + .of_match_table = sl28cpld_pwm_of_match,
    + },
    +};
    +module_platform_driver(sl28cpld_pwm_driver);
    +
    +MODULE_DESCRIPTION("sl28cpld PWM Driver");
    +MODULE_AUTHOR("Michael Walle <michael@walle.cc>");
    +MODULE_LICENSE("GPL");
    --
    2.20.1
    \
     
     \ /
      Last update: 2020-07-06 19:58    [W:6.003 / U:0.016 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site