[PATCH v2 2/2] pwm: add T-HEAD PWM driver

Jisheng Zhang
2023-10-04T09:39:52Z

T-HEAD SoCs such as the TH1520 contain a PWM controller used
to control the LCD backlight, fan and so on. Add driver for it.

Signed-off-by: Jisheng Zhang <jszhang@kernel.org>
---
MAINTAINERS | 1 +
drivers/pwm/Kconfig | 11 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-thead.c | 274 ++++++++++++++++++++++++++++++++++++++++
4 files changed, 287 insertions(+)
create mode 100644 drivers/pwm/pwm-thead.c

diff --git a/MAINTAINERS b/MAINTAINERS
index d55e40060c46..86cf0926dbfc 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -18482,6 +18482,7 @@ L: linux-riscv@lists.infradead.org
S: Maintained
F: arch/riscv/boot/dts/thead/
F: drivers/usb/dwc3/dwc3-thead.c
+F: drivers/pwm/pwm-thead.c

RNBD BLOCK DRIVERS
M: Md. Haris Iqbal <haris.iqbal@ionos.com>
diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 8ebcddf91f7b..428fa365a19a 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -637,6 +637,17 @@ config PWM_TEGRA
To compile this driver as a module, choose M here: the module
will be called pwm-tegra.

+config PWM_THEAD
+ tristate "T-HEAD PWM support"
+ depends on ARCH_THEAD || COMPILE_TEST
+ depends on HAS_IOMEM
+ help
+ Generic PWM framework driver for the PWFM controller found on THEAD
+ SoCs.
+
+ To compile this driver as a module, choose M here: the module
+ will be called pwm-thead.
+
config PWM_TIECAP
tristate "ECAP PWM support"
depends on ARCH_OMAP2PLUS || ARCH_DAVINCI_DA8XX || ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index c822389c2a24..4c317e6316e8 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -59,6 +59,7 @@ obj-$(CONFIG_PWM_STMPE) += pwm-stmpe.o
obj-$(CONFIG_PWM_SUN4I) += pwm-sun4i.o
obj-$(CONFIG_PWM_SUNPLUS) += pwm-sunplus.o
obj-$(CONFIG_PWM_TEGRA) += pwm-tegra.o
+obj-$(CONFIG_PWM_THEAD) += pwm-thead.o
obj-$(CONFIG_PWM_TIECAP) += pwm-tiecap.o
obj-$(CONFIG_PWM_TIEHRPWM) += pwm-tiehrpwm.o
obj-$(CONFIG_PWM_TWL) += pwm-twl.o
diff --git a/drivers/pwm/pwm-thead.c b/drivers/pwm/pwm-thead.c
new file mode 100644
index 000000000000..ba1e3a4f1027
--- /dev/null
+++ b/drivers/pwm/pwm-thead.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * T-HEAD PWM driver
+ *
+ * Copyright (C) 2021 Alibaba Group Holding Limited.
+ * Copyright (C) 2023 Jisheng Zhang <jszhang@kernel.org>
+ *
+ * Limitations:
+ * - The THEAD_PWM_START bit is only effective when 0 -> 1, which is used to
+ * start the channel, 1 -> 0 doesn't change anything. so 0 % duty cycle is
+ * used to "disable" the channel.
+ * - The PWM_CFG_UPDATE atomically updates and only updates period and duty.
+ * - To update period and duty, PWM_CFG_UPDATE needs to go through 0 -> 1 step,
+ * I.E if PWM_CFG_UPDATE is already 1, it's necessary to clear it to 0
+ * beforehand.
+ * - Polarity can only be changed if never started before.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/pm_runtime.h>
+#include <linux/pwm.h>
+#include <linux/slab.h>
+
+#define THEAD_PWM_MAX_NUM 6
+#define THEAD_PWM_MAX_PERIOD GENMASK(31, 0)
+#define THEAD_PWM_MAX_DUTY GENMASK(31, 0)
+
+#define THEAD_PWM_CHN_BASE(n) ((n) * 0x20)
+#define THEAD_PWM_CTRL(n) (THEAD_PWM_CHN_BASE(n) + 0x00)
+#define THEAD_PWM_RPT(n) (THEAD_PWM_CHN_BASE(n) + 0x04)
+#define THEAD_PWM_PER(n) (THEAD_PWM_CHN_BASE(n) + 0x08)
+#define THEAD_PWM_FP(n) (THEAD_PWM_CHN_BASE(n) + 0x0c)
+#define THEAD_PWM_STATUS(n) (THEAD_PWM_CHN_BASE(n) + 0x10)
+
+/* bit definition PWM_CTRL */
+#define THEAD_PWM_START BIT(0)
+#define THEAD_PWM_SOFT_RST BIT(1)
+#define THEAD_PWM_CFG_UPDATE BIT(2)
+#define THEAD_PWM_INT_EN BIT(3)
+#define THEAD_PWM_MODE_MASK GENMASK(5, 4)
+#define THEAD_PWM_ONE_SHOT_MODE FIELD_PREP(THEAD_PWM_MODE_MASK, 1)
+#define THEAD_PWM_CONTINUOUS_MODE FIELD_PREP(THEAD_PWM_MODE_MASK, 2)
+#define THEAD_PWM_EVTRIG_MASK GENMASK(7, 6)
+#define THEAD_PWM_FPOUT BIT(8)
+#define THEAD_PWM_INFACTOUT BIT(9)
+
+struct thead_pwm_chip {
+ struct pwm_chip chip;
+ void __iomem *mmio_base;
+ struct clk *clk;
+ bool ever_started;
+};
+
+static inline struct thead_pwm_chip *thead_pwm_from_chip(struct pwm_chip *chip)
+{
+ return container_of(chip, struct thead_pwm_chip, chip);
+}
+
+static int thead_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+ const struct pwm_state *state)
+{
+ struct thead_pwm_chip *priv = thead_pwm_from_chip(chip);
+ u64 period_cycle, duty_cycle, rate;
+ u32 val;
+
+ /* if ever started, can't change the polarity */
+ if (priv->ever_started && state->polarity != pwm->state.polarity)
+ return -EINVAL;
+
+ if (!state->enabled) {
+ if (pwm->state.enabled) {
+ val = readl(priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+ val &= ~THEAD_PWM_CFG_UPDATE;
+ writel(val, priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+
+ writel(0, priv->mmio_base + THEAD_PWM_FP(pwm->hwpwm));
+
+ val |= THEAD_PWM_CFG_UPDATE;
+ writel(val, priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+ }
+ return 0;
+ }
+
+ if (!pwm->state.enabled)
+ pm_runtime_get_sync(chip->dev);
+
+ val = readl(priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+ val &= ~THEAD_PWM_CFG_UPDATE;
+
+ if (state->polarity == PWM_POLARITY_INVERSED)
+ val &= ~THEAD_PWM_FPOUT;
+ else
+ val |= THEAD_PWM_FPOUT;
+
+ writel(val, priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+
+ rate = clk_get_rate(priv->clk);
+ /*
+ * The following calculations might overflow if clk is bigger
+ * than 1 GHz. In practise it's 24MHz, so this limitation
+ * is only theoretic.
+ */
+ if (rate > (u64)NSEC_PER_SEC)
+ return -EINVAL;
+
+ period_cycle = mul_u64_u64_div_u64(rate, state->period, NSEC_PER_SEC);
+ if (period_cycle > THEAD_PWM_MAX_PERIOD)
+ period_cycle = THEAD_PWM_MAX_PERIOD;
+ /*
+ * With limitation above we have period_cycle <= THEAD_PWM_MAX_PERIOD,
+ * so this cannot overflow.
+ */
+ writel((u32)period_cycle, priv->mmio_base + THEAD_PWM_PER(pwm->hwpwm));
+
+ duty_cycle = mul_u64_u64_div_u64(rate, state->duty_cycle, NSEC_PER_SEC);
+ if (duty_cycle > THEAD_PWM_MAX_DUTY)
+ duty_cycle = THEAD_PWM_MAX_DUTY;
+ /*
+ * With limitation above we have duty_cycle <= THEAD_PWM_MAX_PERIOD,
+ * so this cannot overflow.
+ */
+ writel((u32)duty_cycle, priv->mmio_base + THEAD_PWM_FP(pwm->hwpwm));
+
+ val |= THEAD_PWM_CFG_UPDATE;
+ writel(val, priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+
+ if (!pwm->state.enabled) {
+ val |= THEAD_PWM_START;
+ writel(val, priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+ priv->ever_started = true;
+ }
+
+ return 0;
+}
+
+static int thead_pwm_get_state(struct pwm_chip *chip, struct pwm_device *pwm,
+ struct pwm_state *state)
+{
+ struct thead_pwm_chip *priv = thead_pwm_from_chip(chip);
+ u64 rate = clk_get_rate(priv->clk);
+ u32 val;
+
+ pm_runtime_get_sync(chip->dev);
+
+ val = readl(priv->mmio_base + THEAD_PWM_CTRL(pwm->hwpwm));
+ state->enabled = !!(val & THEAD_PWM_START);
+ if (val & THEAD_PWM_FPOUT)
+ state->polarity = PWM_POLARITY_NORMAL;
+ else
+ state->polarity = PWM_POLARITY_INVERSED;
+
+ val = readl(priv->mmio_base + THEAD_PWM_PER(pwm->hwpwm));
+ /*
+ * val 32 bits, multiply NSEC_PER_SEC, won't overflow.
+ */
+ state->period = DIV64_U64_ROUND_UP((u64)val * NSEC_PER_SEC, rate);
+
+ val = readl(priv->mmio_base + THEAD_PWM_FP(pwm->hwpwm));
+ /*
+ * val 32 bits, multiply NSEC_PER_SEC, won't overflow.
+ */
+ state->duty_cycle = DIV64_U64_ROUND_UP((u64)val * NSEC_PER_SEC, rate);
+
+ pm_runtime_put_sync(chip->dev);
+
+ return 0;
+}
+
+static const struct pwm_ops thead_pwm_ops = {
+ .apply = thead_pwm_apply,
+ .get_state = thead_pwm_get_state,
+ .owner = THIS_MODULE,
+};
+
+static int __maybe_unused thead_pwm_runtime_suspend(struct device *dev)
+{
+ struct thead_pwm_chip *priv = dev_get_drvdata(dev);
+
+ clk_disable_unprepare(priv->clk);
+
+ return 0;
+}
+
+static int __maybe_unused thead_pwm_runtime_resume(struct device *dev)
+{
+ struct thead_pwm_chip *priv = dev_get_drvdata(dev);
+ int ret;
+
+ ret = clk_prepare_enable(priv->clk);
+ if (ret) {
+ dev_err(dev, "failed to enable pwm clock(%d)\n", ret);
+ return ret;
+ }
+
+ return 0;
+}
+
+static int thead_pwm_probe(struct platform_device *pdev)
+{
+ u32 val = THEAD_PWM_INFACTOUT | THEAD_PWM_FPOUT | THEAD_PWM_CONTINUOUS_MODE;
+ struct thead_pwm_chip *priv;
+ int ret, i;
+
+ priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+ if (!priv)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, priv);
+
+ priv->mmio_base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(priv->mmio_base))
+ return PTR_ERR(priv->mmio_base);
+
+ priv->clk = devm_clk_get_enabled(&pdev->dev, NULL);
+ if (IS_ERR(priv->clk))
+ return PTR_ERR(priv->clk);
+
+ priv->chip.ops = &thead_pwm_ops;
+ priv->chip.dev = &pdev->dev;
+ priv->chip.npwm = THEAD_PWM_MAX_NUM;
+
+ /* set normal polarity and other proper bits for all channels */
+ for (i = 0; i < priv->chip.npwm; i++)
+ writel(val, priv->mmio_base + THEAD_PWM_CTRL(i));
+
+ ret = devm_pwmchip_add(&pdev->dev, &priv->chip);
+ if (ret)
+ return ret;
+
+ pm_runtime_enable(&pdev->dev);
+
+ return 0;
+}
+
+static void thead_pwm_remove(struct platform_device *pdev)
+{
+ pm_runtime_disable(&pdev->dev);
+}
+
+static const struct of_device_id thead_pwm_dt_ids[] = {
+ {.compatible = "thead,th1520-pwm",},
+ {/* sentinel */}
+};
+MODULE_DEVICE_TABLE(of, thead_pwm_dt_ids);
+
+static const struct dev_pm_ops thead_pwm_pm_ops = {
+ SET_RUNTIME_PM_OPS(thead_pwm_runtime_suspend, thead_pwm_runtime_resume, NULL)
+};
+
+static struct platform_driver thead_pwm_driver = {
+ .driver = {
+ .name = "thead-pwm",
+ .of_match_table = thead_pwm_dt_ids,
+ .pm = &thead_pwm_pm_ops,
+ },
+ .probe = thead_pwm_probe,
+ .remove_new = thead_pwm_remove,
+};
+module_platform_driver(thead_pwm_driver);
+
+MODULE_AUTHOR("Wei Liu <lw312886@linux.alibaba.com>");
+MODULE_AUTHOR("Jisheng Zhang <jszhang@kernel.org>");
+MODULE_DESCRIPTION("T-HEAD pwm driver");
+MODULE_LICENSE("GPL v2");
--
2.40.1