[PATCH v2 09/16] pwm: add support for sl28cpld PWM controller

Michael Walle
2020-04-02T20:37:38Z

This adds support for the PWM controller of the sl28cpld board
management controller. This is part of a multi-function device driver.

Signed-off-by: Michael Walle <michael@walle.cc>
---
drivers/pwm/Kconfig | 10 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-sl28cpld.c | 203 +++++++++++++++++++++++++++++++++++++
3 files changed, 214 insertions(+)
create mode 100644 drivers/pwm/pwm-sl28cpld.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index eebbc917ac97..5673e5e8b0c3 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -427,6 +427,16 @@ 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 sl28 PWM support"
+ depends on MFD_SL28CPLD
+ 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 9a475073dafc..2c2b569dcde9 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..c6b372bf45fa
--- /dev/null
+++ b/drivers/pwm/pwm-sl28cpld.c
@@ -0,0 +1,203 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * sl28cpld PWM driver.
+ *
+ * Copyright 2019 Kontron Europe GmbH
+ */
+
+#include <linux/bitfield.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of_device.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 inline struct sl28cpld_pwm *to_sl28cpld_pwm(struct pwm_chip *chip)
+{
+ return container_of(chip, struct sl28cpld_pwm, pwm_chip);
+}
+
+static void sl28cpld_pwm_get_state(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct sl28cpld_pwm *spc = to_sl28cpld_pwm(chip);
+ static struct sl28cpld_pwm_config *config;
+ unsigned int reg;
+ unsigned long cycle;
+ unsigned int mode;
+
+ regmap_read(spc->regmap, spc->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(spc->regmap, spc->offset + PWM_CYCLE, &reg);
+ cycle = reg * config->period_ns;
+ state->duty_cycle = DIV_ROUND_CLOSEST_ULL(cycle,
+ 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 *spc = to_sl28cpld_pwm(chip);
+ struct sl28cpld_pwm_config *config;
+ unsigned long long cycle;
+ int ret;
+ int mode;
+ u8 ctrl;
+
+ /* update config, first search best matching 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 = state->duty_cycle * config->max_duty_cycle;
+ do_div(cycle, state->period);
+
+ /*
+ * The hardware doesn't allow to set max_duty_cycle if the
+ * 250Hz mode is enabled. But since this is "all-high" output
+ * just use the 500Hz mode with the duty cycle to max value.
+ */
+ 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(spc->regmap, spc->offset + PWM_CTRL, ctrl);
+ if (ret)
+ return ret;
+
+ return regmap_write(spc->regmap, spc->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 *pwm;
+ struct pwm_chip *chip;
+ struct resource *res;
+ int ret;
+
+ if (!pdev->dev.parent)
+ return -ENODEV;
+
+ pwm = devm_kzalloc(&pdev->dev, sizeof(*pwm), GFP_KERNEL);
+ if (!pwm)
+ return -ENOMEM;
+
+ pwm->regmap = dev_get_regmap(pdev->dev.parent, NULL);
+ if (!pwm->regmap)
+ return -ENODEV;
+
+ res = platform_get_resource(pdev, IORESOURCE_REG, 0);
+ if (!res)
+ return -EINVAL;
+ pwm->offset = res->start;
+
+ /* initialize struct gpio_chip */
+ chip = &pwm->pwm_chip;
+ chip->dev = &pdev->dev;
+ chip->ops = &sl28cpld_pwm_ops;
+ chip->base = -1;
+ chip->npwm = 1;
+
+ ret = pwmchip_add(&pwm->pwm_chip);
+ if (ret < 0)
+ return ret;
+
+ platform_set_drvdata(pdev, pwm);
+
+ return 0;
+}
+
+static int sl28cpld_pwm_remove(struct platform_device *pdev)
+{
+ struct sl28cpld_pwm *pwm = platform_get_drvdata(pdev);
+
+ return pwmchip_remove(&pwm->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 const struct platform_device_id sl28cpld_pwm_id_table[] = {
+ {"sl28cpld-gpio"},
+ {},
+};
+MODULE_DEVICE_TABLE(platform, sl28cpld_pwm_id_table);
+
+static struct platform_driver sl28cpld_pwm_driver = {
+ .probe = sl28cpld_pwm_probe,
+ .remove = sl28cpld_pwm_remove,
+ .id_table = sl28cpld_pwm_id_table,
+ .driver = {
+ .name = KBUILD_MODNAME,
+ .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