[PATCH v2 2/5] pwm: Add support for the MSTAR MSC313 PWM

Romain Perier
2022-09-07T13:13:08Z

From: Daniel Palmer <daniel@0x0f.com>

This adds support for the PWM block on the Mstar MSC313e SoCs and newer.

Signed-off-by: Daniel Palmer <daniel@0x0f.com>
Co-developed-by: Romain Perier <romain.perier@gmail.com>
Signed-off-by: Romain Perier <romain.perier@gmail.com>
---
MAINTAINERS | 1 +
drivers/pwm/Kconfig | 9 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-msc313e.c | 269 ++++++++++++++++++++++++++++++++++++++
4 files changed, 280 insertions(+)
create mode 100644 drivers/pwm/pwm-msc313e.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 9d7f64dc0efe..c3b39b09097c 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2439,6 +2439,7 @@ F: arch/arm/mach-mstar/
F: drivers/clk/mstar/
F: drivers/clocksource/timer-msc313e.c
F: drivers/gpio/gpio-msc313.c
+F: drivers/pwm/pwm-msc313e.c
F: drivers/rtc/rtc-msc313.c
F: drivers/watchdog/msc313e_wdt.c
F: include/dt-bindings/clock/mstar-*
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 60d13a949bc5..8049fd03a821 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -372,6 +372,15 @@ config PWM_MESON
To compile this driver as a module, choose M here: the module
will be called pwm-meson.

+config PWM_MSC313E
+ tristate "MStar MSC313e PWM support"
+ depends on ARCH_MSTARV7 || COMPILE_TEST
+ help
+ Generic PWM framework driver for MSTAR MSC313e.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-msc313e.
+
config PWM_MTK_DISP
tristate "MediaTek display PWM driver"
depends on ARCH_MEDIATEK || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 7bf1a29f02b8..bc285c054f2a 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -62,4 +62,5 @@ obj-$(CONFIG_PWM_TWL) += pwm-twl.o
obj-$(CONFIG_PWM_TWL_LED) += pwm-twl-led.o
obj-$(CONFIG_PWM_VISCONTI) += pwm-visconti.o
obj-$(CONFIG_PWM_VT8500) += pwm-vt8500.o
+obj-$(CONFIG_PWM_MSC313E) += pwm-msc313e.o
obj-$(CONFIG_PWM_XILINX) += pwm-xilinx.o
diff --git a/drivers/pwm/pwm-msc313e.c b/drivers/pwm/pwm-msc313e.c
new file mode 100644
index 000000000000..a71f39ba66c3
--- /dev/null
+++ b/drivers/pwm/pwm-msc313e.c
@@ -0,0 +1,269 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2021 Daniel Palmer <daniel@thingy.jp>
+ * Copyright (C) 2022 Romain Perier <romain.perier@gmail.com>
+ */
+
+#include <linux/clk.h>
+#include <linux/of_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+
+#define DRIVER_NAME "msc313e-pwm"
+
+#define CHANNEL_OFFSET 0x80
+#define REG_DUTY 0x8
+#define REG_PERIOD 0x10
+#define REG_DIV 0x18
+#define REG_CTRL 0x1c
+#define REG_SWRST 0x1fc
+
+struct msc313e_pwm_channel {
+ struct regmap_field *clkdiv;
+ struct regmap_field *polarity;
+ struct regmap_field *dutyl;
+ struct regmap_field *dutyh;
+ struct regmap_field *periodl;
+ struct regmap_field *periodh;
+ struct regmap_field *swrst;
+};
+
+struct msc313e_pwm {
+ struct regmap *regmap;
+ struct pwm_chip pwmchip;
+ struct clk *clk;
+ struct msc313e_pwm_channel channels[];
+};
+
+struct msc313e_pwm_info {
+ unsigned int channels;
+};
+
+#define to_msc313e_pwm(ptr) container_of(ptr, struct msc313e_pwm, pwmchip)
+
+static const struct regmap_config msc313e_pwm_regmap_config = {
+ .reg_bits = 16,
+ .val_bits = 16,
+ .reg_stride = 4,
+};
+
+static const struct msc313e_pwm_info msc313e_data = {
+ .channels = 8,
+};
+
+static const struct msc313e_pwm_info ssd20xd_data = {
+ .channels = 4,
+};
+
+static void msc313e_pwm_writecounter(struct regmap_field *low, struct regmap_field *high, u32 value)
+{
+ /* The bus that connects the CPU to the peripheral registers splits 32 bit registers into
+ * two 16bit registers placed 4 bytes apart. It's the hardware design they used. The counter
+ * we are about to write has this contrainst.
+ */
+ regmap_field_write(low, value & 0xffff);
+ regmap_field_write(high, value >> 16);
+}
+
+static void msc313e_pwm_readcounter(struct regmap_field *low, struct regmap_field *high, u32 *value)
+{
+ unsigned int val = 0;
+
+ regmap_field_read(low, &val);
+ *value = val;
+ regmap_field_read(high, &val);
+ *value = (val << 16) | *value;
+}
+
+static int msc313e_pwm_config(struct pwm_chip *chip, struct pwm_device *device,
+ int duty_ns, int period_ns)
+{
+ struct msc313e_pwm *pwm = to_msc313e_pwm(chip);
+ unsigned long long nspertick = DIV_ROUND_DOWN_ULL(NSEC_PER_SEC, clk_get_rate(pwm->clk));
+ struct msc313e_pwm_channel *channel = &pwm->channels[device->hwpwm];
+ unsigned long long div = 1;
+
+ /* Fit the period into the period register by prescaling the clk */
+ while (DIV_ROUND_DOWN_ULL(period_ns, nspertick) > 0x3ffff) {
+ div++;
+ if (div > (0xffff + 1)) {
+ /* Force clk div to the maximum allowed value */
+ div = 0xffff;
+ break;
+ }
+ nspertick = DIV_ROUND_DOWN_ULL(nspertick, div);
+ }
+
+ regmap_field_write(channel->clkdiv, div - 1);
+ msc313e_pwm_writecounter(channel->dutyl, channel->dutyh,
+ DIV_ROUND_DOWN_ULL(duty_ns, nspertick));
+ msc313e_pwm_writecounter(channel->periodl, channel->periodh,
+ DIV_ROUND_DOWN_ULL(period_ns, nspertick));
+ return 0;
+};
+
+static int msc313e_pwm_set_polarity(struct pwm_chip *chip, struct pwm_device *device,
+ enum pwm_polarity polarity)
+{
+ struct msc313e_pwm *pwm = to_msc313e_pwm(chip);
+ struct msc313e_pwm_channel *channel = &pwm->channels[device->hwpwm];
+ unsigned int pol = 0;
+
+ if (polarity == PWM_POLARITY_INVERSED)
+ pol = 1;
+ regmap_field_update_bits(channel->polarity, 1, pol);
+
+ return 0;
+}
+
+static int msc313e_pwm_enable(struct pwm_chip *chip, struct pwm_device *device)
+{
+ struct msc313e_pwm *pwm = to_msc313e_pwm(chip);
+ struct msc313e_pwm_channel *channel = &pwm->channels[device->hwpwm];
+ int ret;
+
+ ret = clk_prepare_enable(pwm->clk);
+ if (ret)
+ return ret;
+ return regmap_field_write(channel->swrst, 0);
+}
+
+static int msc313e_pwm_disable(struct pwm_chip *chip, struct pwm_device *device)
+{
+ struct msc313e_pwm *pwm = to_msc313e_pwm(chip);
+ struct msc313e_pwm_channel *channel = &pwm->channels[device->hwpwm];
+ int ret;
+
+ ret = regmap_field_write(channel->swrst, 1);
+ clk_disable_unprepare(pwm->clk);
+ return ret;
+}
+
+static int msc313e_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_state *state)
+{
+ int ret;
+
+ if (state->enabled) {
+ if (!pwm->state.enabled) {
+ ret = msc313e_pwm_enable(chip, pwm);
+ if (ret)
+ return ret;
+ }
+ msc313e_pwm_set_polarity(chip, pwm, state->polarity);
+ msc313e_pwm_config(chip, pwm, state->duty_cycle, state->period);
+ } else if (pwm->state.enabled) {
+ ret = msc313e_pwm_disable(chip, pwm);
+ }
+ return 0;
+}
+
+static void msc313e_get_state(struct pwm_chip *chip, struct pwm_device *device,
+ struct pwm_state *state)
+{
+ struct msc313e_pwm *pwm = to_msc313e_pwm(chip);
+ struct msc313e_pwm_channel *channel = &pwm->channels[device->hwpwm];
+ unsigned long long nspertick = DIV_ROUND_DOWN_ULL(NSEC_PER_SEC, clk_get_rate(pwm->clk));
+ unsigned int val = 0;
+
+ regmap_field_read(channel->polarity, &val);
+ state->polarity = val ? PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
+
+ regmap_field_read(channel->swrst, &val);
+ state->enabled = val == 0 ? true : false;
+
+ msc313e_pwm_readcounter(channel->dutyl, channel->dutyh, &val);
+ state->duty_cycle = val * nspertick;
+
+ msc313e_pwm_readcounter(channel->periodl, channel->periodh, &val);
+ state->period = val * nspertick;
+}
+
+static const struct pwm_ops msc313e_pwm_ops = {
+ .apply = msc313e_apply,
+ .get_state = msc313e_get_state,
+ .owner = THIS_MODULE
+};
+
+static int msc313e_pwm_probe(struct platform_device *pdev)
+{
+ const struct msc313e_pwm_info *match_data;
+ struct device *dev = &pdev->dev;
+ struct msc313e_pwm *pwm;
+ __iomem void *base;
+ int i;
+
+ match_data = of_device_get_match_data(dev);
+ if (!match_data)
+ return -EINVAL;
+
+ base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ pwm = devm_kzalloc(dev, struct_size(pwm, channels, match_data->channels), GFP_KERNEL);
+ if (!pwm)
+ return -ENOMEM;
+
+ pwm->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(pwm->clk))
+ return dev_err_probe(dev, PTR_ERR(pwm->clk), "Cannot get clk\n");
+
+ pwm->regmap = devm_regmap_init_mmio(dev, base, &msc313e_pwm_regmap_config);
+ if (IS_ERR(pwm->regmap))
+ return dev_err_probe(dev, PTR_ERR(pwm->regmap), "Cannot get regmap\n");
+
+ for (i = 0; i < match_data->channels; i++) {
+ unsigned int offset = CHANNEL_OFFSET * i;
+ struct reg_field div_clkdiv_field = REG_FIELD(offset + REG_DIV, 0, 7);
+ struct reg_field ctrl_polarity_field = REG_FIELD(offset + REG_CTRL, 4, 4);
+ struct reg_field dutyl_field = REG_FIELD(offset + REG_DUTY, 0, 15);
+ struct reg_field dutyh_field = REG_FIELD(offset + REG_DUTY + 4, 0, 2);
+ struct reg_field periodl_field = REG_FIELD(offset + REG_PERIOD, 0, 15);
+ struct reg_field periodh_field = REG_FIELD(offset + REG_PERIOD + 4, 0, 2);
+ struct reg_field swrst_field = REG_FIELD(REG_SWRST, i, i);
+
+ pwm->channels[i].clkdiv = devm_regmap_field_alloc(dev, pwm->regmap,
+ div_clkdiv_field);
+ pwm->channels[i].polarity = devm_regmap_field_alloc(dev, pwm->regmap,
+ ctrl_polarity_field);
+ pwm->channels[i].dutyl = devm_regmap_field_alloc(dev, pwm->regmap, dutyl_field);
+ pwm->channels[i].dutyh = devm_regmap_field_alloc(dev, pwm->regmap, dutyh_field);
+ pwm->channels[i].periodl = devm_regmap_field_alloc(dev, pwm->regmap, periodl_field);
+ pwm->channels[i].periodh = devm_regmap_field_alloc(dev, pwm->regmap, periodh_field);
+ pwm->channels[i].swrst = devm_regmap_field_alloc(dev, pwm->regmap, swrst_field);
+
+ /* Channels are enabled on boot, disable it until the pwm subsystem re-enable it
+ * explicitly
+ */
+ regmap_field_write(pwm->channels[i].swrst, 1);
+ }
+
+ pwm->pwmchip.dev = dev;
+ pwm->pwmchip.ops = &msc313e_pwm_ops;
+ pwm->pwmchip.npwm = match_data->channels;
+
+ platform_set_drvdata(pdev, pwm);
+
+ return devm_pwmchip_add(dev, &pwm->pwmchip);
+}
+
+static const struct of_device_id msc313e_pwm_dt_ids[] = {
+ { .compatible = "mstar,msc313e-pwm", .data = &msc313e_data },
+ { .compatible = "mstar,ssd20xd-pwm", .data = &ssd20xd_data },
+ {},
+};
+MODULE_DEVICE_TABLE(of, msc313e_pwm_dt_ids);
+
+static struct platform_driver msc313e_pwm_driver = {
+ .probe = msc313e_pwm_probe,
+ .driver = {
+ .name = DRIVER_NAME,
+ .of_match_table = msc313e_pwm_dt_ids,
+ },
+};
+module_platform_driver(msc313e_pwm_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Mstar MSC313e PWM driver");
+MODULE_AUTHOR("Daniel Palmer <daniel@thingy.jp>");
--
2.35.1