Merge branch 'pwm/th1520' into pwm/for-next

4 files changed, 413 insertions, 1 deletions

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 17fbfe04adfb..bf2d101f67a1 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -758,6 +758,17 @@ config PWM_TEGRA
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-tegra.
 
+config PWM_TH1520
+	tristate "TH1520 PWM support"
+	depends on RUST
+	select RUST_PWM_ABSTRACTIONS
+	help
+	  This option enables the driver for the PWM controller found on the
+	  T-HEAD TH1520 SoC.
+
+	  To compile this driver as a module, choose M here; the module
+	  will be called pwm-th1520. If you are unsure, say N.
+
 config PWM_TIECAP
 	tristate "ECAP PWM support"
 	depends on ARCH_OMAP2PLUS || ARCH_DAVINCI_DA8XX || ARCH_KEYSTONE || ARCH_K3 || COMPILE_TEST
@@ -829,4 +840,16 @@ config PWM_XILINX
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-xilinx.
 
+ config RUST_PWM_ABSTRACTIONS
+	bool
+	depends on RUST
+	help
+	  This option enables the safe Rust abstraction layer for the PWM
+	  subsystem. It provides idiomatic wrappers and traits necessary for
+	  writing PWM controller drivers in Rust.
+
+	  The abstractions handle resource management (like memory and reference
+	  counting) and provide safe interfaces to the underlying C core,
+	  allowing driver logic to be written in safe Rust.
+
 endif
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 044049516256..0dc0d2b69025 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -69,6 +69,7 @@ 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-$(CONFIG_PWM_TH1520)	+= pwm_th1520.o
 obj-$(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/core.c b/drivers/pwm/core.c
index 7dd1cf2ba402..cd06229db394 100644
--- a/drivers/pwm/core.c
+++ b/drivers/pwm/core.c
@@ -1608,12 +1608,13 @@ void pwmchip_put(struct pwm_chip *chip)
 }
 EXPORT_SYMBOL_GPL(pwmchip_put);
 
-static void pwmchip_release(struct device *pwmchip_dev)
+void pwmchip_release(struct device *pwmchip_dev)
 {
 	struct pwm_chip *chip = pwmchip_from_dev(pwmchip_dev);
 
 	kfree(chip);
 }
+EXPORT_SYMBOL_GPL(pwmchip_release);
 
 struct pwm_chip *pwmchip_alloc(struct device *parent, unsigned int npwm, size_t sizeof_priv)
 {
diff --git a/drivers/pwm/pwm_th1520.rs b/drivers/pwm/pwm_th1520.rs
new file mode 100644
index 000000000000..955c359b07fb
--- /dev/null
+++ b/drivers/pwm/pwm_th1520.rs
@@ -0,0 +1,387 @@
+// SPDX-License-Identifier: GPL-2.0
+// Copyright (c) 2025 Samsung Electronics Co., Ltd.
+// Author: Michal Wilczynski <m.wilczynski@samsung.com>
+
+//! Rust T-HEAD TH1520 PWM driver
+//!
+//! Limitations:
+//! - The period and duty cycle are controlled by 32-bit hardware registers,
+//!   limiting the maximum resolution.
+//! - The driver supports continuous output mode only; one-shot mode is not
+//!   implemented.
+//! - The controller hardware provides up to 6 PWM channels.
+//! - Reconfiguration is glitch free - new period and duty cycle values are
+//!   latched and take effect at the start of the next period.
+//! - Polarity is handled via a simple hardware inversion bit; arbitrary
+//!   duty cycle offsets are not supported.
+//! - Disabling a channel is achieved by configuring its duty cycle to zero to
+//!   produce a static low output. Clearing the `start` does not reliably
+//!   force the static inactive level defined by the `INACTOUT` bit. Hence
+//!   this method is not used in this driver.
+//!
+
+use core::ops::Deref;
+use kernel::{
+    c_str,
+    clk::Clk,
+    device::{Bound, Core, Device},
+    devres,
+    io::mem::IoMem,
+    of, platform,
+    prelude::*,
+    pwm, time,
+};
+
+const TH1520_MAX_PWM_NUM: u32 = 6;
+
+// Register offsets
+const fn th1520_pwm_chn_base(n: u32) -> usize {
+    (n * 0x20) as usize
+}
+
+const fn th1520_pwm_ctrl(n: u32) -> usize {
+    th1520_pwm_chn_base(n)
+}
+
+const fn th1520_pwm_per(n: u32) -> usize {
+    th1520_pwm_chn_base(n) + 0x08
+}
+
+const fn th1520_pwm_fp(n: u32) -> usize {
+    th1520_pwm_chn_base(n) + 0x0c
+}
+
+// Control register bits
+const TH1520_PWM_START: u32 = 1 << 0;
+const TH1520_PWM_CFG_UPDATE: u32 = 1 << 2;
+const TH1520_PWM_CONTINUOUS_MODE: u32 = 1 << 5;
+const TH1520_PWM_FPOUT: u32 = 1 << 8;
+
+const TH1520_PWM_REG_SIZE: usize = 0xB0;
+
+fn ns_to_cycles(ns: u64, rate_hz: u64) -> u64 {
+    const NSEC_PER_SEC_U64: u64 = time::NSEC_PER_SEC as u64;
+
+    (match ns.checked_mul(rate_hz) {
+        Some(product) => product,
+        None => u64::MAX,
+    }) / NSEC_PER_SEC_U64
+}
+
+fn cycles_to_ns(cycles: u64, rate_hz: u64) -> u64 {
+    const NSEC_PER_SEC_U64: u64 = time::NSEC_PER_SEC as u64;
+
+    // TODO: Replace with a kernel helper like `mul_u64_u64_div_u64_roundup`
+    // once available in Rust.
+    let numerator = cycles
+        .saturating_mul(NSEC_PER_SEC_U64)
+        .saturating_add(rate_hz - 1);
+
+    numerator / rate_hz
+}
+
+/// Hardware-specific waveform representation for TH1520.
+#[derive(Copy, Clone, Debug, Default)]
+struct Th1520WfHw {
+    period_cycles: u32,
+    duty_cycles: u32,
+    ctrl_val: u32,
+    enabled: bool,
+}
+
+/// The driver's private data struct. It holds all necessary devres managed resources.
+#[pin_data(PinnedDrop)]
+struct Th1520PwmDriverData {
+    #[pin]
+    iomem: devres::Devres<IoMem<TH1520_PWM_REG_SIZE>>,
+    clk: Clk,
+}
+
+// This `unsafe` implementation is a temporary necessity because the underlying `kernel::clk::Clk`
+// type does not yet expose `Send` and `Sync` implementations. This block should be removed
+// as soon as the clock abstraction provides these guarantees directly.
+// TODO: Remove those unsafe impl's when Clk will support them itself.
+
+// SAFETY: The `devres` framework requires the driver's private data to be `Send` and `Sync`.
+// We can guarantee this because the PWM core synchronizes all callbacks, preventing concurrent
+// access to the contained `iomem` and `clk` resources.
+unsafe impl Send for Th1520PwmDriverData {}
+
+// SAFETY: The same reasoning applies as for `Send`. The PWM core's synchronization
+// guarantees that it is safe for multiple threads to have shared access (`&self`)
+// to the driver data during callbacks.
+unsafe impl Sync for Th1520PwmDriverData {}
+
+impl pwm::PwmOps for Th1520PwmDriverData {
+    type WfHw = Th1520WfHw;
+
+    fn round_waveform_tohw(
+        chip: &pwm::Chip<Self>,
+        _pwm: &pwm::Device,
+        wf: &pwm::Waveform,
+    ) -> Result<pwm::RoundedWaveform<Self::WfHw>> {
+        let data = chip.drvdata();
+        let mut status = 0;
+
+        if wf.period_length_ns == 0 {
+            dev_dbg!(chip.device(), "Requested period is 0, disabling PWM.\n");
+
+            return Ok(pwm::RoundedWaveform {
+                status: 0,
+                hardware_waveform: Th1520WfHw {
+                    enabled: false,
+                    ..Default::default()
+                },
+            });
+        }
+
+        let rate_hz = data.clk.rate().as_hz() as u64;
+
+        let mut period_cycles = ns_to_cycles(wf.period_length_ns, rate_hz).min(u64::from(u32::MAX));
+
+        if period_cycles == 0 {
+            dev_dbg!(
+                chip.device(),
+                "Requested period {} ns is too small for clock rate {} Hz, rounding up.\n",
+                wf.period_length_ns,
+                rate_hz
+            );
+
+            period_cycles = 1;
+            status = 1;
+        }
+
+        let mut duty_cycles = ns_to_cycles(wf.duty_length_ns, rate_hz).min(u64::from(u32::MAX));
+
+        let mut ctrl_val = TH1520_PWM_CONTINUOUS_MODE;
+
+        let is_inversed = wf.duty_length_ns > 0
+            && wf.duty_offset_ns > 0
+            && wf.duty_offset_ns >= wf.period_length_ns.saturating_sub(wf.duty_length_ns);
+        if is_inversed {
+            duty_cycles = period_cycles - duty_cycles;
+        } else {
+            ctrl_val |= TH1520_PWM_FPOUT;
+        }
+
+        let wfhw = Th1520WfHw {
+            // The cast is safe because the value was clamped with `.min(u64::from(u32::MAX))`.
+            period_cycles: period_cycles as u32,
+            duty_cycles: duty_cycles as u32,
+            ctrl_val,
+            enabled: true,
+        };
+
+        dev_dbg!(
+            chip.device(),
+            "Requested: {}/{} ns [+{} ns] -> HW: {}/{} cycles, ctrl 0x{:x}, rate {} Hz\n",
+            wf.duty_length_ns,
+            wf.period_length_ns,
+            wf.duty_offset_ns,
+            wfhw.duty_cycles,
+            wfhw.period_cycles,
+            wfhw.ctrl_val,
+            rate_hz
+        );
+
+        Ok(pwm::RoundedWaveform {
+            status,
+            hardware_waveform: wfhw,
+        })
+    }
+
+    fn round_waveform_fromhw(
+        chip: &pwm::Chip<Self>,
+        _pwm: &pwm::Device,
+        wfhw: &Self::WfHw,
+        wf: &mut pwm::Waveform,
+    ) -> Result {
+        let data = chip.drvdata();
+        let rate_hz = data.clk.rate().as_hz() as u64;
+
+        if wfhw.period_cycles == 0 {
+            dev_dbg!(
+                chip.device(),
+                "HW state has zero period, reporting as disabled.\n"
+            );
+            *wf = pwm::Waveform::default();
+            return Ok(());
+        }
+
+        wf.period_length_ns = cycles_to_ns(u64::from(wfhw.period_cycles), rate_hz);
+
+        let duty_cycles = u64::from(wfhw.duty_cycles);
+
+        if (wfhw.ctrl_val & TH1520_PWM_FPOUT) != 0 {
+            wf.duty_length_ns = cycles_to_ns(duty_cycles, rate_hz);
+            wf.duty_offset_ns = 0;
+        } else {
+            let period_cycles = u64::from(wfhw.period_cycles);
+            let original_duty_cycles = period_cycles.saturating_sub(duty_cycles);
+
+            // For an inverted signal, `duty_length_ns` is the high time (period - low_time).
+            wf.duty_length_ns = cycles_to_ns(original_duty_cycles, rate_hz);
+            // The offset is the initial low time, which is what the hardware register provides.
+            wf.duty_offset_ns = cycles_to_ns(duty_cycles, rate_hz);
+        }
+
+        Ok(())
+    }
+
+    fn read_waveform(
+        chip: &pwm::Chip<Self>,
+        pwm: &pwm::Device,
+        parent_dev: &Device<Bound>,
+    ) -> Result<Self::WfHw> {
+        let data = chip.drvdata();
+        let hwpwm = pwm.hwpwm();
+        let iomem_accessor = data.iomem.access(parent_dev)?;
+        let iomap = iomem_accessor.deref();
+
+        let ctrl = iomap.try_read32(th1520_pwm_ctrl(hwpwm))?;
+        let period_cycles = iomap.try_read32(th1520_pwm_per(hwpwm))?;
+        let duty_cycles = iomap.try_read32(th1520_pwm_fp(hwpwm))?;
+
+        let wfhw = Th1520WfHw {
+            period_cycles,
+            duty_cycles,
+            ctrl_val: ctrl,
+            enabled: duty_cycles != 0,
+        };
+
+        dev_dbg!(
+            chip.device(),
+            "PWM-{}: read_waveform: Read hw state - period: {}, duty: {}, ctrl: 0x{:x}, enabled: {}",
+            hwpwm,
+            wfhw.period_cycles,
+            wfhw.duty_cycles,
+            wfhw.ctrl_val,
+            wfhw.enabled
+        );
+
+        Ok(wfhw)
+    }
+
+    fn write_waveform(
+        chip: &pwm::Chip<Self>,
+        pwm: &pwm::Device,
+        wfhw: &Self::WfHw,
+        parent_dev: &Device<Bound>,
+    ) -> Result {
+        let data = chip.drvdata();
+        let hwpwm = pwm.hwpwm();
+        let iomem_accessor = data.iomem.access(parent_dev)?;
+        let iomap = iomem_accessor.deref();
+        let duty_cycles = iomap.try_read32(th1520_pwm_fp(hwpwm))?;
+        let was_enabled = duty_cycles != 0;
+
+        if !wfhw.enabled {
+            dev_dbg!(chip.device(), "PWM-{}: Disabling channel.\n", hwpwm);
+            if was_enabled {
+                iomap.try_write32(wfhw.ctrl_val, th1520_pwm_ctrl(hwpwm))?;
+                iomap.try_write32(0, th1520_pwm_fp(hwpwm))?;
+                iomap.try_write32(
+                    wfhw.ctrl_val | TH1520_PWM_CFG_UPDATE,
+                    th1520_pwm_ctrl(hwpwm),
+                )?;
+            }
+            return Ok(());
+        }
+
+        iomap.try_write32(wfhw.ctrl_val, th1520_pwm_ctrl(hwpwm))?;
+        iomap.try_write32(wfhw.period_cycles, th1520_pwm_per(hwpwm))?;
+        iomap.try_write32(wfhw.duty_cycles, th1520_pwm_fp(hwpwm))?;
+        iomap.try_write32(
+            wfhw.ctrl_val | TH1520_PWM_CFG_UPDATE,
+            th1520_pwm_ctrl(hwpwm),
+        )?;
+
+        // The `TH1520_PWM_START` bit must be written in a separate, final transaction, and
+        // only when enabling the channel from a disabled state.
+        if !was_enabled {
+            iomap.try_write32(wfhw.ctrl_val | TH1520_PWM_START, th1520_pwm_ctrl(hwpwm))?;
+        }
+
+        dev_dbg!(
+            chip.device(),
+            "PWM-{}: Wrote {}/{} cycles",
+            hwpwm,
+            wfhw.duty_cycles,
+            wfhw.period_cycles,
+        );
+
+        Ok(())
+    }
+}
+
+#[pinned_drop]
+impl PinnedDrop for Th1520PwmDriverData {
+    fn drop(self: Pin<&mut Self>) {
+        self.clk.disable_unprepare();
+    }
+}
+
+struct Th1520PwmPlatformDriver;
+
+kernel::of_device_table!(
+    OF_TABLE,
+    MODULE_OF_TABLE,
+    <Th1520PwmPlatformDriver as platform::Driver>::IdInfo,
+    [(of::DeviceId::new(c_str!("thead,th1520-pwm")), ())]
+);
+
+impl platform::Driver for Th1520PwmPlatformDriver {
+    type IdInfo = ();
+    const OF_ID_TABLE: Option<of::IdTable<Self::IdInfo>> = Some(&OF_TABLE);
+
+    fn probe(
+        pdev: &platform::Device<Core>,
+        _id_info: Option<&Self::IdInfo>,
+    ) -> Result<Pin<KBox<Self>>> {
+        let dev = pdev.as_ref();
+        let request = pdev.io_request_by_index(0).ok_or(ENODEV)?;
+
+        let clk = Clk::get(dev, None)?;
+
+        clk.prepare_enable()?;
+
+        // TODO: Get exclusive ownership of the clock to prevent rate changes.
+        // The Rust equivalent of `clk_rate_exclusive_get()` is not yet available.
+        // This should be updated once it is implemented.
+        let rate_hz = clk.rate().as_hz();
+        if rate_hz == 0 {
+            dev_err!(dev, "Clock rate is zero\n");
+            return Err(EINVAL);
+        }
+
+        if rate_hz > time::NSEC_PER_SEC as usize {
+            dev_err!(
+                dev,
+                "Clock rate {} Hz is too high, not supported.\n",
+                rate_hz
+            );
+            return Err(EINVAL);
+        }
+
+        let chip = pwm::Chip::new(
+            dev,
+            TH1520_MAX_PWM_NUM,
+            try_pin_init!(Th1520PwmDriverData {
+                iomem <- request.iomap_sized::<TH1520_PWM_REG_SIZE>(),
+                clk <- clk,
+            }),
+        )?;
+
+        pwm::Registration::register(dev, chip)?;
+
+        Ok(KBox::new(Th1520PwmPlatformDriver, GFP_KERNEL)?.into())
+    }
+}
+
+kernel::module_pwm_platform_driver! {
+    type: Th1520PwmPlatformDriver,
+    name: "pwm-th1520",
+    authors: ["Michal Wilczynski <m.wilczynski@samsung.com>"],
+    description: "T-HEAD TH1520 PWM driver",
+    license: "GPL v2",
+}