[PATCH v2 2/3] pwm: rp1: Add RP1 PWM controller driver

Andrea della Porta
2026-04-10T14:07:06Z

From: Naushir Patuck <naush@raspberrypi.com>

The Raspberry Pi RP1 southbridge features an embedded PWM
controller with 4 output channels, alongside an RPM interface
to read the fan speed on the Raspberry Pi 5.

Add the supporting driver.

Signed-off-by: Naushir Patuck <naush@raspberrypi.com>
Co-developed-by: Stanimir Varbanov <svarbanov@suse.de>
Signed-off-by: Stanimir Varbanov <svarbanov@suse.de>
Signed-off-by: Andrea della Porta <andrea.porta@suse.com>
---
drivers/pwm/Kconfig | 9 ++
drivers/pwm/Makefile | 1 +
drivers/pwm/pwm-rp1.c | 344 ++++++++++++++++++++++++++++++++++++++++++
3 files changed, 354 insertions(+)
create mode 100644 drivers/pwm/pwm-rp1.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 6f3147518376a..32031f2af75af 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -625,6 +625,15 @@ config PWM_ROCKCHIP
Generic PWM framework driver for the PWM controller found on
Rockchip SoCs.

+config PWM_RASPBERRYPI_RP1
+ bool "RP1 PWM support"
+ depends on MISC_RP1 || COMPILE_TEST
+ depends on HAS_IOMEM
+ select REGMAP_MMIO
+ select MFD_SYSCON
+ help
+ PWM framework driver for Raspberry Pi RP1 controller.
+
config PWM_SAMSUNG
tristate "Samsung PWM support"
depends on PLAT_SAMSUNG || ARCH_S5PV210 || ARCH_EXYNOS || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 0dc0d2b69025d..59f29f60f9123 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -56,6 +56,7 @@ obj-$(CONFIG_PWM_RENESAS_RZG2L_GPT) += pwm-rzg2l-gpt.o
obj-$(CONFIG_PWM_RENESAS_RZ_MTU3) += pwm-rz-mtu3.o
obj-$(CONFIG_PWM_RENESAS_TPU) += pwm-renesas-tpu.o
obj-$(CONFIG_PWM_ROCKCHIP) += pwm-rockchip.o
+obj-$(CONFIG_PWM_RASPBERRYPI_RP1) += pwm-rp1.o
obj-$(CONFIG_PWM_SAMSUNG) += pwm-samsung.o
obj-$(CONFIG_PWM_SIFIVE) += pwm-sifive.o
obj-$(CONFIG_PWM_SL28CPLD) += pwm-sl28cpld.o
diff --git a/drivers/pwm/pwm-rp1.c b/drivers/pwm/pwm-rp1.c
new file mode 100644
index 0000000000000..b88c697d9567e
--- /dev/null
+++ b/drivers/pwm/pwm-rp1.c
@@ -0,0 +1,344 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * pwm-rp1.c
+ *
+ * Raspberry Pi RP1 PWM.
+ *
+ * Copyright © 2026 Raspberry Pi Ltd.
+ *
+ * Author: Naushir Patuck (naush@raspberrypi.com)
+ *
+ * Based on the pwm-bcm2835 driver by:
+ * Bart Tanghe <bart.tanghe@thomasmore.be>
+ *
+ * Datasheet: https://pip-assets.raspberrypi.com/categories/892-raspberry-pi-5/documents/RP-008370-DS-1-rp1-peripherals.pdf?disposition=inline
+ *
+ * Limitations:
+ * - Channels can be enabled/disabled and their duty cycle and period can
+ * be updated glitchlessly. Update are synchronized with the next strobe
+ * at the end of the current period of the respective channel, once the
+ * update bit is set. The update flag is global, not per-channel.
+ * - Channels are phase-capable, but on RPi5, the firmware can use a channel
+ * phase register to report the RPM of the fan connected to that PWM
+ * channel. As a result, phase control will be ignored for now.
+ */
+
+#include <linux/bitops.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/pwm.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+
+#define RP1_PWM_GLOBAL_CTRL 0x000
+#define RP1_PWM_CHANNEL_CTRL(x) (0x014 + ((x) * 0x10))
+#define RP1_PWM_RANGE(x) (0x018 + ((x) * 0x10))
+#define RP1_PWM_PHASE(x) (0x01C + ((x) * 0x10))
+#define RP1_PWM_DUTY(x) (0x020 + ((x) * 0x10))
+
+/* 8:FIFO_POP_MASK + 0:Trailing edge M/S modulation */
+#define RP1_PWM_CHANNEL_DEFAULT (BIT(8) + BIT(0))
+#define RP1_PWM_CHANNEL_ENABLE(x) BIT(x)
+#define RP1_PWM_POLARITY BIT(3)
+#define RP1_PWM_SET_UPDATE BIT(31)
+#define RP1_PWM_MODE_MASK GENMASK(1, 0)
+
+#define RP1_PWM_NUM_PWMS 4
+
+struct rp1_pwm {
+ struct regmap *regmap;
+ struct clk *clk;
+ unsigned long clk_rate;
+ bool clk_enabled;
+};
+
+struct rp1_pwm_waveform {
+ u32 period_ticks;
+ u32 duty_ticks;
+ bool enabled;
+ bool inverted_polarity;
+};
+
+static const struct regmap_config rp1_pwm_regmap_config = {
+ .reg_bits = 32,
+ .val_bits = 32,
+ .reg_stride = 4,
+ .max_register = 0x60,
+};
+
+static void rp1_pwm_apply_config(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
+ u32 value;
+
+ /* update the changed registers on the next strobe to avoid glitches */
+ regmap_read(rp1->regmap, RP1_PWM_GLOBAL_CTRL, &value);
+ value |= RP1_PWM_SET_UPDATE;
+ regmap_write(rp1->regmap, RP1_PWM_GLOBAL_CTRL, value);
+}
+
+static int rp1_pwm_request(struct pwm_chip *chip, struct pwm_device *pwm)
+{
+ struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
+
+ /* init channel to reset defaults */
+ regmap_write(rp1->regmap, RP1_PWM_CHANNEL_CTRL(pwm->hwpwm), RP1_PWM_CHANNEL_DEFAULT);
+ return 0;
+}
+
+static int rp1_pwm_round_waveform_tohw(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ const struct pwm_waveform *wf,
+ void *_wfhw)
+{
+ struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
+ struct rp1_pwm_waveform *wfhw = _wfhw;
+ u64 clk_rate = rp1->clk_rate;
+ u64 ticks;
+
+ ticks = mul_u64_u64_div_u64(wf->period_length_ns, clk_rate, NSEC_PER_SEC);
+
+ if (ticks > U32_MAX)
+ ticks = U32_MAX;
+ wfhw->period_ticks = ticks;
+
+ if (wf->duty_offset_ns + wf->duty_length_ns >= wf->period_length_ns) {
+ ticks = mul_u64_u64_div_u64(wf->period_length_ns - wf->duty_length_ns,
+ clk_rate, NSEC_PER_SEC);
+ wfhw->inverted_polarity = true;
+ } else {
+ ticks = mul_u64_u64_div_u64(wf->duty_length_ns, clk_rate, NSEC_PER_SEC);
+ wfhw->inverted_polarity = false;
+ }
+
+ if (ticks > wfhw->period_ticks)
+ ticks = wfhw->period_ticks;
+ wfhw->duty_ticks = ticks;
+
+ wfhw->enabled = !!wfhw->duty_ticks;
+
+ return 0;
+}
+
+static int rp1_pwm_round_waveform_fromhw(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ const void *_wfhw,
+ struct pwm_waveform *wf)
+{
+ struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
+ const struct rp1_pwm_waveform *wfhw = _wfhw;
+ u64 clk_rate = rp1->clk_rate;
+ u32 ticks;
+
+ memset(wf, 0, sizeof(*wf));
+
+ if (!wfhw->enabled)
+ return 0;
+
+ wf->period_length_ns = DIV_ROUND_UP_ULL((u64)wfhw->period_ticks * NSEC_PER_SEC, clk_rate);
+
+ if (wfhw->inverted_polarity) {
+ wf->duty_length_ns = DIV_ROUND_UP_ULL((u64)wfhw->duty_ticks * NSEC_PER_SEC,
+ clk_rate);
+ } else {
+ wf->duty_offset_ns = DIV_ROUND_UP_ULL((u64)wfhw->duty_ticks * NSEC_PER_SEC,
+ clk_rate);
+ ticks = wfhw->period_ticks - wfhw->duty_ticks;
+ wf->duty_length_ns = DIV_ROUND_UP_ULL((u64)ticks * NSEC_PER_SEC, clk_rate);
+ }
+
+ return 0;
+}
+
+static int rp1_pwm_write_waveform(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ const void *_wfhw)
+{
+ struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
+ const struct rp1_pwm_waveform *wfhw = _wfhw;
+ u32 value;
+
+ /* set period and duty cycle */
+ regmap_write(rp1->regmap,
+ RP1_PWM_RANGE(pwm->hwpwm), wfhw->period_ticks);
+ regmap_write(rp1->regmap,
+ RP1_PWM_DUTY(pwm->hwpwm), wfhw->duty_ticks);
+
+ /* set polarity */
+ regmap_read(rp1->regmap, RP1_PWM_CHANNEL_CTRL(pwm->hwpwm), &value);
+ if (!wfhw->inverted_polarity)
+ value &= ~RP1_PWM_POLARITY;
+ else
+ value |= RP1_PWM_POLARITY;
+ regmap_write(rp1->regmap, RP1_PWM_CHANNEL_CTRL(pwm->hwpwm), value);
+
+ /* enable/disable */
+ regmap_read(rp1->regmap, RP1_PWM_GLOBAL_CTRL, &value);
+ if (wfhw->enabled)
+ value |= RP1_PWM_CHANNEL_ENABLE(pwm->hwpwm);
+ else
+ value &= ~RP1_PWM_CHANNEL_ENABLE(pwm->hwpwm);
+ regmap_write(rp1->regmap, RP1_PWM_GLOBAL_CTRL, value);
+
+ rp1_pwm_apply_config(chip, pwm);
+
+ return 0;
+}
+
+static int rp1_pwm_read_waveform(struct pwm_chip *chip,
+ struct pwm_device *pwm,
+ void *_wfhw)
+{
+ struct rp1_pwm *rp1 = pwmchip_get_drvdata(chip);
+ struct rp1_pwm_waveform *wfhw = _wfhw;
+ u32 value;
+
+ regmap_read(rp1->regmap, RP1_PWM_GLOBAL_CTRL, &value);
+ wfhw->enabled = !!(value & RP1_PWM_CHANNEL_ENABLE(pwm->hwpwm));
+
+ regmap_read(rp1->regmap, RP1_PWM_CHANNEL_CTRL(pwm->hwpwm), &value);
+ wfhw->inverted_polarity = !!(value & RP1_PWM_POLARITY);
+
+ if (wfhw->enabled) {
+ regmap_read(rp1->regmap, RP1_PWM_RANGE(pwm->hwpwm), &wfhw->period_ticks);
+ regmap_read(rp1->regmap, RP1_PWM_DUTY(pwm->hwpwm), &wfhw->duty_ticks);
+ } else {
+ wfhw->period_ticks = 0;
+ wfhw->duty_ticks = 0;
+ }
+
+ return 0;
+}
+
+static const struct pwm_ops rp1_pwm_ops = {
+ .sizeof_wfhw = sizeof(struct rp1_pwm_waveform),
+ .request = rp1_pwm_request,
+ .round_waveform_tohw = rp1_pwm_round_waveform_tohw,
+ .round_waveform_fromhw = rp1_pwm_round_waveform_fromhw,
+ .read_waveform = rp1_pwm_read_waveform,
+ .write_waveform = rp1_pwm_write_waveform,
+};
+
+static int rp1_pwm_probe(struct platform_device *pdev)
+{
+ struct device *dev = &pdev->dev;
+ struct device_node *np = dev->of_node;
+ unsigned long clk_rate;
+ struct pwm_chip *chip;
+ void __iomem *base;
+ struct rp1_pwm *rp1;
+ int ret;
+
+ chip = devm_pwmchip_alloc(dev, RP1_PWM_NUM_PWMS, sizeof(*rp1));
+ if (IS_ERR(chip))
+ return PTR_ERR(chip);
+
+ rp1 = pwmchip_get_drvdata(chip);
+
+ base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(base))
+ return PTR_ERR(base);
+
+ rp1->regmap = devm_regmap_init_mmio(dev, base, &rp1_pwm_regmap_config);
+ if (IS_ERR(rp1->regmap))
+ return dev_err_probe(dev, PTR_ERR(rp1->regmap), "Cannot initialize regmap\n");
+
+ ret = of_syscon_register_regmap(np, rp1->regmap);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to register syscon\n");
+
+ rp1->clk = devm_clk_get(dev, NULL);
+ if (IS_ERR(rp1->clk))
+ return dev_err_probe(dev, PTR_ERR(rp1->clk), "Clock not found\n");
+
+ ret = clk_prepare_enable(rp1->clk);
+ if (ret)
+ return dev_err_probe(dev, ret, "Failed to enable clock\n");
+ rp1->clk_enabled = true;
+
+ ret = devm_clk_rate_exclusive_get(dev, rp1->clk);
+ if (ret) {
+ dev_err_probe(dev, ret, "Fail to get exclusive rate\n");
+ goto err_disable_clk;
+ }
+
+ clk_rate = clk_get_rate(rp1->clk);
+ if (!clk_rate) {
+ ret = dev_err_probe(dev, -EINVAL, "Failed to get clock rate\n");
+ goto err_disable_clk;
+ }
+ rp1->clk_rate = clk_rate;
+
+ chip->ops = &rp1_pwm_ops;
+
+ platform_set_drvdata(pdev, chip);
+
+ ret = devm_pwmchip_add(dev, chip);
+ if (ret) {
+ dev_err_probe(dev, ret, "Failed to register PWM chip\n");
+ goto err_disable_clk;
+ }
+
+ return 0;
+
+err_disable_clk:
+ clk_disable_unprepare(rp1->clk);
+
+ return ret;
+}
+
+static int rp1_pwm_suspend(struct device *dev)
+{
+ struct rp1_pwm *rp1 = dev_get_drvdata(dev);
+
+ if (rp1->clk_enabled) {
+ clk_disable_unprepare(rp1->clk);
+ rp1->clk_enabled = false;
+ }
+
+ return 0;
+}
+
+static int rp1_pwm_resume(struct device *dev)
+{
+ struct rp1_pwm *rp1 = dev_get_drvdata(dev);
+ int ret;
+
+ ret = clk_prepare_enable(rp1->clk);
+ if (ret) {
+ dev_err(dev, "Failed to enable clock on resume: %d\n", ret);
+ return ret;
+ }
+
+ rp1->clk_enabled = true;
+
+ return 0;
+}
+
+static DEFINE_SIMPLE_DEV_PM_OPS(rp1_pwm_pm_ops, rp1_pwm_suspend, rp1_pwm_resume);
+
+static const struct of_device_id rp1_pwm_of_match[] = {
+ { .compatible = "raspberrypi,rp1-pwm" },
+ { /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, rp1_pwm_of_match);
+
+static struct platform_driver rp1_pwm_driver = {
+ .probe = rp1_pwm_probe,
+ .driver = {
+ .name = "rp1-pwm",
+ .of_match_table = rp1_pwm_of_match,
+ .pm = pm_ptr(&rp1_pwm_pm_ops),
+ .suppress_bind_attrs = true,
+ },
+};
+module_platform_driver(rp1_pwm_driver);
+
+MODULE_DESCRIPTION("RP1 PWM driver");
+MODULE_AUTHOR("Naushir Patuck <naush@raspberrypi.com>");
+MODULE_AUTHOR("Andrea della Porta <andrea.porta@suse.com>");
+MODULE_LICENSE("GPL");
--
2.35.3