[PATCH v7 0/2] pwm: add support for NXPs high-side switch MC33XS2410

[PATCH v7 0/2] pwm: add support for NXPs high-side switch MC33XS2410

[Dimitri Fedrau]

The MC33XS2410 is a four channel high-side switch. Featuring advanced
monitoring and control function, the device is operational from 3.0 V to
60 V. The device is controlled by SPI port for configuration.

Changes in V2:
  - fix title in devicetree binding
  - fix commit message in devicetree binding patch
  - remove external clock from pwms and create clocks property
  - switch to unevaluatedProperties: false
  - add missing properties for complete example:
    - pwm-names
    - pwms
    - interrupts
    - clocks

Changes in V3:
  - Add description of the general behaviour of the device (limitations)
  - Drop unused defines
  - Add ranges comments for defines with parameters
  - Drop MC33XS2410_PERIOD_MAX, MC33XS2410_PERIOD_MIN defines
  - Drop mc33xs2410_period variable
  - Round down when calculating period and duty cycle
  - Use switch instead of loop when calculating frequency
  - Removed ret variable in mc33xs2410_pwm_get_freq
  - Handle all accesses in a single call to spi_sync_transfer
  - Fix comments in function mc33xs2410_pwm_get_period
  - Fix call pwm_set_relative_duty_cycle(state, ret, 255), instead
    pwm_set_relative_duty_cycle(state, val[1] + 1, 256);
  - Use devm_pwmchip_alloc
  - Fix typo s/Transitition/Transition/
  - Drop driver_data
  - Removed patch for direct inputs from series
  - Tested with PWM_DEBUG enabled, didn't before !

Changes in V4:
  - removed include of math.h, already included in math64.h
  - removed include of mutex.h, no mutexes are used
  - added include of bitfield.h(FIELD_GET, FIELD_PREP), fixes errors
    discovered by kernel test robot
  - cast parameters in DIV_ROUND_UP to u32, fixes errors discovered by
    kernel test robot

Changes in V5:
  - Fix comment in mc33xs2410_pwm_get_freq, selecting steps instead of
    period
  - Add comment in mc33xs2410_pwm_get_relative_duty_cycle that duty_cycle
    cannot overflow and and period is not zero, guaranteed by the caller
  - Hardware emits a low level when disabled, disable if duty_cycle = 0 is
    requested.
  - Fix complaints when PWM_DEBUG enabled, round-down division in
    mc33xs2410_pwm_apply and round-up in mc33xs2410_pwm_get_state.
  - Add comment for disabling watchdog in probe

Changes in V6:
  - Add link to manual
  - Redefine MC33XS2410_GLB_CTRL_MODE_MASK as MC33XS2410_GLB_CTRL_MODE and
    MC33XS2410_GLB_CTRL_NORMAL_MODE as MC33XS2410_GLB_CTRL_MODE_NORMAL
  - Remove define MC33XS2410_MIN_PERIOD_STEP(x) as there is no need for
    parameters and use instead MC33XS2410_MIN_PERIOD
  - Rename function to_pwm_mc33xs2410_chip to mc33xs2410_from_chip
  - Add comment in mc33xs2410_pwm_get_freq why count should be rounded up
  - Fix incorrect comment in mc33xs2410_pwm_get_period
  - Rename steps variable to doubled_steps in function
    mc33xs2410_pwm_get_freq
  - remove cast in mc33xs2410_pwm_set_relative_duty_cycle
  - remove duty_cycle from if in mc33xs2410_pwm_set_relative_duty_cycle

Changes in V7:
  - Add empty lines for defines with parameter
  - Hardcode into:
    - MC33XS2410_PWM_DC1 -> MC33XS2410_PWM_DC
    - MC33XS2410_PWM_FREQ1 -> MC33XS2410_PWM_FREQ
    - MC33XS2410_MAX_PERIOD_STEP0 -> MC33XS2410_MAX_PERIOD_STEP
  - Rename:
    - MC33XS2410_MIN_PERIOD -> MC33XS2410_PWM_MIN_PERIOD
    - MC33XS2410_MAX_PERIOD_STEP -> MC33XS2410_PWM_MAX_PERIOD
    - MC33XS2410_WR -> MC33XS2410_FRAME_IN_ADDR_WR
    - MC33XS2410_RD_CTRL -> MC33XS2410_FRAME_IN_DATA_RD
    - MC33XS2410_RD_DATA_MASK -> MC33XS2410_FRAME_OUT_DATA
  - Change range for MC33XS2410_PWM_CTRL1_POL_INV
  - Drop mask suffixes
  - Switch to unsigned int len in mc33xs2410_write_regs and
    mc33xs2410_read_regs
  - Remove define MC33XS2410_WORD_LEN
  - Use a single spi transfer in mc33xs2410_write_regs and
    mc33xs2410_read_regs by using SPI_CS_WORD and 16 bits per word
  - Break the line in the argument list instead of having a static in its
    own for mc33xs2410_read_reg definition
  - Remove u32 cast mc33xs2410_pwm_get_period
  - Unroll mc33xs2410_pwm_get_relative_duty_cycle
  - Unroll mc33xs2410_pwm_set_relative_duty_cycle and remove check for
    state->enabled
  - Remove ctrl[x] and use instead a u8 flag which indicates from which
    registers to read

Dimitri Fedrau (2):
  dt-bindings: pwm: add support for MC33XS2410
  pwm: add support for NXPs high-side switch MC33XS2410

 .../bindings/pwm/nxp,mc33xs2410.yaml          | 118 ++++++
 drivers/pwm/Kconfig                           |  12 +
 drivers/pwm/Makefile                          |   1 +
 drivers/pwm/pwm-mc33xs2410.c                  | 388 ++++++++++++++++++
 4 files changed, 519 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/nxp,mc33xs2410.yaml
 create mode 100644 drivers/pwm/pwm-mc33xs2410.c

-- 
2.39.5

[PATCH v7 1/2] dt-bindings: pwm: add support for MC33XS2410

[Dimitri Fedrau]

Adding documentation for NXPs MC33XS2410 high side switch.

Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
---
 .../bindings/pwm/nxp,mc33xs2410.yaml          | 118 ++++++++++++++++++
 1 file changed, 118 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/pwm/nxp,mc33xs2410.yaml

diff --git a/Documentation/devicetree/bindings/pwm/nxp,mc33xs2410.yaml b/Documentation/devicetree/bindings/pwm/nxp,mc33xs2410.yaml
new file mode 100644
index 000000000000..1729fe5c3dfb
--- /dev/null
+++ b/Documentation/devicetree/bindings/pwm/nxp,mc33xs2410.yaml
@@ -0,0 +1,118 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/pwm/nxp,mc33xs2410.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: High-side switch MC33XS2410
+
+maintainers:
+  - Dimitri Fedrau <dima.fedrau@gmail.com>
+
+allOf:
+  - $ref: pwm.yaml#
+  - $ref: /schemas/spi/spi-peripheral-props.yaml#
+
+properties:
+  compatible:
+    const: nxp,mc33xs2410
+
+  reg:
+    maxItems: 1
+
+  spi-max-frequency:
+    maximum: 10000000
+
+  spi-cpha: true
+
+  spi-cs-setup-delay-ns:
+    minimum: 100
+    default: 100
+
+  spi-cs-hold-delay-ns:
+    minimum: 10
+    default: 10
+
+  spi-cs-inactive-delay-ns:
+    minimum: 300
+    default: 300
+
+  reset-gpios:
+    description:
+      GPIO connected to the active low reset pin.
+    maxItems: 1
+
+  "#pwm-cells":
+    const: 3
+
+  pwm-names:
+    items:
+      - const: di0
+      - const: di1
+      - const: di2
+      - const: di3
+
+  pwms:
+    description:
+      Direct inputs(di0-3) are used to directly turn-on or turn-off the
+      outputs.
+    maxItems: 4
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    description:
+      The external clock can be used if the internal clock doesn't meet
+      timing requirements over temperature and voltage operating range.
+    maxItems: 1
+
+  vdd-supply:
+    description:
+      Logic supply voltage
+
+  vspi-supply:
+    description:
+      Supply voltage for SPI
+
+  vpwr-supply:
+    description:
+      Power switch supply
+
+required:
+  - compatible
+  - reg
+
+unevaluatedProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    spi {
+        #address-cells = <1>;
+        #size-cells = <0>;
+
+       pwm@0 {
+           compatible = "nxp,mc33xs2410";
+           reg = <0x0>;
+           spi-max-frequency = <4000000>;
+           spi-cpha;
+           spi-cs-setup-delay-ns = <100>;
+           spi-cs-hold-delay-ns = <10>;
+           spi-cs-inactive-delay-ns = <300>;
+           reset-gpios = <&gpio3 22 GPIO_ACTIVE_LOW>;
+           #pwm-cells = <3>;
+           pwm-names = "di0", "di1", "di2", "di3";
+           pwms = <&pwm0 0 1000000>,
+                  <&pwm1 0 1000000>,
+                  <&pwm2 0 1000000>,
+                  <&pwm3 0 1000000>;
+           interrupt-parent = <&gpio0>;
+           interrupts = <31 IRQ_TYPE_LEVEL_LOW>;
+           clocks = <&clk_ext_fixed>;
+           vdd-supply = <&reg_3v3>;
+           vspi-supply = <&reg_3v3>;
+           vpwr-supply = <&reg_24v0>;
+       };
+    };
-- 
2.39.5

[PATCH v7 2/2] pwm: add support for NXPs high-side switch MC33XS2410

[Dimitri Fedrau]

The MC33XS2410 is a four channel high-side switch. Featuring advanced
monitoring and control function, the device is operational from 3.0 V to
60 V. The device is controlled by SPI port for configuration.

Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
---
 drivers/pwm/Kconfig          |  12 ++
 drivers/pwm/Makefile         |   1 +
 drivers/pwm/pwm-mc33xs2410.c | 388 +++++++++++++++++++++++++++++++++++
 3 files changed, 401 insertions(+)
 create mode 100644 drivers/pwm/pwm-mc33xs2410.c

diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
index 0915c1e7df16..f513513f9b2f 100644
--- a/drivers/pwm/Kconfig
+++ b/drivers/pwm/Kconfig
@@ -411,6 +411,18 @@ config PWM_LPSS_PLATFORM
 	  To compile this driver as a module, choose M here: the module
 	  will be called pwm-lpss-platform.
 
+config PWM_MC33XS2410
+	tristate "MC33XS2410 PWM support"
+	depends on OF
+	depends on SPI
+	help
+	  NXP MC33XS2410 high-side switch driver. The MC33XS2410 is a four
+	  channel high-side switch. The device is operational from 3.0 V
+	  to 60 V. The device is controlled by SPI port for configuration.
+
+	  To compile this driver as a module, choose M here: the module
+	  will be called pwm-mc33xs2410.
+
 config PWM_MESON
 	tristate "Amlogic Meson PWM driver"
 	depends on ARCH_MESON || COMPILE_TEST
diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
index 9081e0c0e9e0..c75deeeace40 100644
--- a/drivers/pwm/Makefile
+++ b/drivers/pwm/Makefile
@@ -36,6 +36,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
 obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
 obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
 obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
+obj-$(CONFIG_PWM_MC33XS2410)	+= pwm-mc33xs2410.o
 obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
 obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
 obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
diff --git a/drivers/pwm/pwm-mc33xs2410.c b/drivers/pwm/pwm-mc33xs2410.c
new file mode 100644
index 000000000000..97cf31ef608a
--- /dev/null
+++ b/drivers/pwm/pwm-mc33xs2410.c
@@ -0,0 +1,388 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2024 Liebherr-Electronics and Drives GmbH
+ *
+ * Reference Manual : https://www.nxp.com/docs/en/data-sheet/MC33XS2410.pdf
+ *
+ * Limitations:
+ * - Supports frequencies between 0.5Hz and 2048Hz with following steps:
+ *   - 0.5 Hz steps from 0.5 Hz to 32 Hz
+ *   - 2 Hz steps from 2 Hz to 128 Hz
+ *   - 8 Hz steps from 8 Hz to 512 Hz
+ *   - 32 Hz steps from 32 Hz to 2048 Hz
+ * - Cannot generate a 0 % duty cycle.
+ * - Always produces low output if disabled.
+ * - Configuration isn't atomic. When changing polarity, duty cycle or period
+ *   the data is taken immediately, counters not being affected, resulting in a
+ *   behavior of the output pin that is neither the old nor the new state,
+ *   rather something in between.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/delay.h>
+#include <linux/err.h>
+#include <linux/math64.h>
+#include <linux/minmax.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/pwm.h>
+
+#include <linux/spi/spi.h>
+
+#define MC33XS2410_GLB_CTRL		0x00
+#define MC33XS2410_GLB_CTRL_MODE	GENMASK(7, 6)
+#define MC33XS2410_GLB_CTRL_MODE_NORMAL	FIELD_PREP(MC33XS2410_GLB_CTRL_MODE, 1)
+
+#define MC33XS2410_PWM_CTRL1		0x05
+/* x in { 1 ... 4 } */
+#define MC33XS2410_PWM_CTRL1_POL_INV(x)	BIT((x - 1))
+
+#define MC33XS2410_PWM_CTRL3		0x07
+/* x in { 1 ... 4 } */
+#define MC33XS2410_PWM_CTRL3_EN(x)	BIT(4 + (x - 1))
+
+/* x in { 1 ... 4 } */
+#define MC33XS2410_PWM_FREQ(x)		(0x08 + (x - 1))
+#define MC33XS2410_PWM_FREQ_STEP	GENMASK(7, 6)
+#define MC33XS2410_PWM_FREQ_COUNT	GENMASK(5, 0)
+
+/* x in { 1 ... 4 } */
+#define MC33XS2410_PWM_DC(x)		(0x0c + (x - 1))
+
+#define MC33XS2410_WDT			0x14
+
+#define MC33XS2410_PWM_MIN_PERIOD	488282
+/* x in { 0 ... 3 } */
+#define MC33XS2410_PWM_MAX_PERIOD(x)	(2000000000 >> (2 * x))
+
+#define MC33XS2410_FRAME_IN_ADDR	GENMASK(15, 8)
+#define MC33XS2410_FRAME_IN_DATA	GENMASK(7, 0)
+#define MC33XS2410_FRAME_IN_ADDR_WR	BIT(7)
+#define MC33XS2410_FRAME_IN_DATA_RD	BIT(7)
+#define MC33XS2410_FRAME_OUT_DATA	GENMASK(13, 0)
+
+#define MC33XS2410_MAX_TRANSFERS	5
+
+struct mc33xs2410_pwm {
+	struct spi_device *spi;
+};
+
+static inline struct mc33xs2410_pwm *mc33xs2410_from_chip(struct pwm_chip *chip)
+{
+	return pwmchip_get_drvdata(chip);
+}
+
+static int mc33xs2410_write_regs(struct spi_device *spi, u8 *reg, u8 *val,
+				 unsigned int len)
+{
+	u16 tx[MC33XS2410_MAX_TRANSFERS];
+	int i;
+
+	if (len > MC33XS2410_MAX_TRANSFERS)
+		return -EINVAL;
+
+	for (i = 0; i < len; i++)
+		tx[i] = FIELD_PREP(MC33XS2410_FRAME_IN_DATA, val[i]) |
+			FIELD_PREP(MC33XS2410_FRAME_IN_ADDR,
+				   MC33XS2410_FRAME_IN_ADDR_WR | reg[i]);
+
+	return spi_write(spi, tx, len * 2);
+}
+
+static int mc33xs2410_read_regs(struct spi_device *spi, u8 *reg, u8 flag,
+				u16 *val, unsigned int len)
+{
+	u16 tx[MC33XS2410_MAX_TRANSFERS];
+	u16 rx[MC33XS2410_MAX_TRANSFERS];
+	struct spi_transfer t = {
+		.tx_buf = tx,
+		.rx_buf = rx,
+	};
+	int i, ret;
+
+	len++;
+	if (len > MC33XS2410_MAX_TRANSFERS)
+		return -EINVAL;
+
+	t.len = len * 2;
+	for (i = 0; i < len - 1; i++)
+		tx[i] = FIELD_PREP(MC33XS2410_FRAME_IN_DATA, flag) |
+			FIELD_PREP(MC33XS2410_FRAME_IN_ADDR, reg[i]);
+
+	ret = spi_sync_transfer(spi, &t, 1);
+	if (ret < 0)
+		return ret;
+
+	for (i = 1; i < len; i++)
+		val[i - 1] = FIELD_GET(MC33XS2410_FRAME_OUT_DATA, rx[i]);
+
+	return 0;
+}
+
+
+static int mc33xs2410_write_reg(struct spi_device *spi, u8 reg, u8 val)
+{
+	return mc33xs2410_write_regs(spi, &reg, &val, 1);
+}
+
+static int mc33xs2410_read_reg(struct spi_device *spi, u8 reg, u16 *val, u8 flag)
+{
+	return mc33xs2410_read_regs(spi, &reg, flag, val, 1);
+}
+
+static int mc33xs2410_read_reg_ctrl(struct spi_device *spi, u8 reg, u16 *val)
+{
+	return mc33xs2410_read_reg(spi, reg, val, MC33XS2410_FRAME_IN_DATA_RD);
+}
+
+static int mc33xs2410_modify_reg(struct spi_device *spi, u8 reg, u8 mask, u8 val)
+{
+	u16 tmp;
+	int ret;
+
+	ret = mc33xs2410_read_reg_ctrl(spi, reg, &tmp);
+	if (ret < 0)
+		return ret;
+
+	tmp &= ~mask;
+	tmp |= val & mask;
+
+	return mc33xs2410_write_reg(spi, reg, tmp);
+}
+
+static u8 mc33xs2410_pwm_get_freq(u64 period)
+{
+	u8 step, count;
+
+	/*
+	 * Check which step is appropriate for the given period, starting with
+	 * the highest frequency(lowest period). Higher frequencies are
+	 * represented with better resolution by the device. Therefore favor
+	 * frequency range with the better resolution to minimize error
+	 * introduced by the frequency steps.
+	 */
+
+	switch (period) {
+	case MC33XS2410_PWM_MIN_PERIOD ... MC33XS2410_PWM_MAX_PERIOD(3):
+		step = 3;
+		break;
+	case MC33XS2410_PWM_MAX_PERIOD(3) + 1 ... MC33XS2410_PWM_MAX_PERIOD(2):
+		step = 2;
+		break;
+	case MC33XS2410_PWM_MAX_PERIOD(2) + 1 ... MC33XS2410_PWM_MAX_PERIOD(1):
+		step = 1;
+		break;
+	case MC33XS2410_PWM_MAX_PERIOD(1) + 1 ... MC33XS2410_PWM_MAX_PERIOD(0):
+		step = 0;
+		break;
+	}
+
+	/*
+	 * Round up here because a higher count results in a higher frequency
+	 * and so a smaller period.
+	 */
+	count = DIV_ROUND_UP((u32)MC33XS2410_PWM_MAX_PERIOD(step), (u32)period);
+	return FIELD_PREP(MC33XS2410_PWM_FREQ_STEP, step) |
+	       FIELD_PREP(MC33XS2410_PWM_FREQ_COUNT, count - 1);
+}
+
+static u64 mc33xs2410_pwm_get_period(u8 reg)
+{
+	u32 freq, code, doubled_steps;
+
+	/*
+	 * steps:
+	 *   - 0 = 0.5Hz
+	 *   - 1 = 2Hz
+	 *   - 2 = 8Hz
+	 *   - 3 = 32Hz
+	 * frequency = (code + 1) x steps.
+	 *
+	 * To avoid losing precision in case steps value is zero, scale the
+	 * steps value for now by two and keep it in mind when calculating the
+	 * period that the frequency had been doubled.
+	 */
+	doubled_steps = 1 << (FIELD_GET(MC33XS2410_PWM_FREQ_STEP, reg) * 2);
+	code = FIELD_GET(MC33XS2410_PWM_FREQ_COUNT, reg);
+	freq = (code + 1) * doubled_steps;
+
+	/* Convert frequency to period, considering the doubled frequency. */
+	return DIV_ROUND_UP(2 * NSEC_PER_SEC, freq);
+}
+
+static int mc33xs2410_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
+				const struct pwm_state *state)
+{
+	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
+	struct spi_device *spi = mc33xs2410->spi;
+	u8 reg[4] = {
+			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
+			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
+			MC33XS2410_PWM_CTRL1,
+			MC33XS2410_PWM_CTRL3
+		    };
+	u64 period, duty_cycle;
+	int ret, rel_dc;
+	u16 rd_val[2];
+	u8 wr_val[4];
+	u8 mask;
+
+	period = min(state->period, MC33XS2410_PWM_MAX_PERIOD(0));
+	if (period < MC33XS2410_PWM_MIN_PERIOD)
+		return -EINVAL;
+
+	ret = mc33xs2410_read_regs(spi, &reg[2], MC33XS2410_FRAME_IN_DATA_RD, rd_val, 2);
+	if (ret < 0)
+		return ret;
+
+	/* frequency */
+	wr_val[0] = mc33xs2410_pwm_get_freq(period);
+	/* Continue calculations with the possibly truncated period */
+	period = mc33xs2410_pwm_get_period(wr_val[0]);
+
+	/* duty cycle */
+	duty_cycle = min(period, state->duty_cycle);
+	rel_dc = div64_u64(duty_cycle * 256, period) - 1;
+	if (rel_dc < 0)
+		wr_val[1] = 0;
+	else
+		wr_val[1] = rel_dc;
+
+	/* polarity */
+	mask = MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm + 1);
+	wr_val[2] = (state->polarity == PWM_POLARITY_INVERSED) ?
+		    (rd_val[0] | mask) : (rd_val[0] & ~mask);
+
+	/* enable output */
+	mask = MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm + 1);
+	wr_val[3] = (state->enabled && rel_dc >= 0) ? (rd_val[1] | mask) :
+						      (rd_val[1] & ~mask);
+
+	return mc33xs2410_write_regs(spi, reg, wr_val, 4);
+}
+
+static int mc33xs2410_pwm_get_state(struct pwm_chip *chip,
+				    struct pwm_device *pwm,
+				    struct pwm_state *state)
+{
+	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
+	struct spi_device *spi = mc33xs2410->spi;
+	u8 reg[4] = {
+			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
+			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
+			MC33XS2410_PWM_CTRL1,
+			MC33XS2410_PWM_CTRL3,
+		    };
+	u16 val[4];
+	int ret;
+
+	ret = mc33xs2410_read_regs(spi, reg, MC33XS2410_FRAME_IN_DATA_RD, val, 4);
+	if (ret < 0)
+		return ret;
+
+	state->period = mc33xs2410_pwm_get_period(val[0]);
+	state->polarity = (val[2] & MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm + 1)) ?
+			  PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
+	state->enabled = !!(val[3] & MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm + 1));
+	state->duty_cycle = DIV_ROUND_UP_ULL((val[1] + 1) * state->period, 256);
+
+	return 0;
+}
+
+static const struct pwm_ops mc33xs2410_pwm_ops = {
+	.apply = mc33xs2410_pwm_apply,
+	.get_state = mc33xs2410_pwm_get_state,
+};
+
+static int mc33xs2410_reset(struct device *dev)
+{
+	struct gpio_desc *reset_gpio;
+
+	reset_gpio = devm_gpiod_get_optional(dev, "reset", GPIOD_OUT_HIGH);
+	if (IS_ERR_OR_NULL(reset_gpio))
+		return PTR_ERR_OR_ZERO(reset_gpio);
+
+	fsleep(1000);
+	gpiod_set_value_cansleep(reset_gpio, 0);
+	/* Wake-up time */
+	fsleep(10000);
+
+	return 0;
+}
+
+static int mc33xs2410_probe(struct spi_device *spi)
+{
+	struct mc33xs2410_pwm *mc33xs2410;
+	struct device *dev = &spi->dev;
+	struct pwm_chip *chip;
+	int ret;
+
+	chip = devm_pwmchip_alloc(dev, 4, sizeof(*mc33xs2410));
+	if (IS_ERR(chip))
+		return PTR_ERR(chip);
+
+	spi->bits_per_word = 16;
+	spi->mode |= SPI_CS_WORD;
+	ret = spi_setup(spi);
+	if (ret < 0)
+		return ret;
+
+	mc33xs2410 = mc33xs2410_from_chip(chip);
+	mc33xs2410->spi = spi;
+	chip->ops = &mc33xs2410_pwm_ops;
+
+	ret = mc33xs2410_reset(dev);
+	if (ret)
+		return ret;
+
+	/*
+	 * Disable watchdog and keep in mind that the watchdog won't trigger a
+	 * reset of the machine when running into an timeout, instead the
+	 * control over the outputs is handed over to the INx input logic
+	 * signals of the device. Disabling it here just deactivates this
+	 * feature until a proper solution is found.
+	 */
+	ret = mc33xs2410_write_reg(spi, MC33XS2410_WDT, 0x0);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to disable watchdog\n");
+
+	/* Transition to normal mode */
+	ret = mc33xs2410_modify_reg(spi, MC33XS2410_GLB_CTRL,
+				    MC33XS2410_GLB_CTRL_MODE,
+				    MC33XS2410_GLB_CTRL_MODE_NORMAL);
+	if (ret < 0)
+		return dev_err_probe(dev, ret,
+				     "Failed to transition to normal mode\n");
+
+	ret = devm_pwmchip_add(dev, chip);
+	if (ret < 0)
+		return dev_err_probe(dev, ret, "Failed to add pwm chip\n");
+
+	return 0;
+}
+
+static const struct spi_device_id mc33xs2410_spi_id[] = {
+	{ "mc33xs2410" },
+	{ }
+};
+MODULE_DEVICE_TABLE(spi, mc33xs2410_spi_id);
+
+static const struct of_device_id mc33xs2410_of_match[] = {
+	{ .compatible = "nxp,mc33xs2410" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mc33xs2410_of_match);
+
+static struct spi_driver mc33xs2410_driver = {
+	.driver = {
+		.name = "mc33xs2410-pwm",
+		.of_match_table = mc33xs2410_of_match,
+	},
+	.probe = mc33xs2410_probe,
+	.id_table = mc33xs2410_spi_id,
+};
+module_spi_driver(mc33xs2410_driver);
+
+MODULE_DESCRIPTION("NXP MC33XS2410 high-side switch driver");
+MODULE_AUTHOR("Dimitri Fedrau <dima.fedrau@gmail.com>");
+MODULE_LICENSE("GPL");
-- 
2.39.5

Re: [PATCH v7 2/2] pwm: add support for NXPs high-side switch MC33XS2410

[Uwe Kleine-König]

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Hello Dimitri,

thanks for your patience. I'm mostly happy now. Just a few minor
comments below:

On Sat, Nov 09, 2024 at 06:41:35PM +0100, Dimitri Fedrau wrote:
> The MC33XS2410 is a four channel high-side switch. Featuring advanced
> monitoring and control function, the device is operational from 3.0 V to
> 60 V. The device is controlled by SPI port for configuration.
> 
> Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
> ---
>  drivers/pwm/Kconfig          |  12 ++
>  drivers/pwm/Makefile         |   1 +
>  drivers/pwm/pwm-mc33xs2410.c | 388 +++++++++++++++++++++++++++++++++++
>  3 files changed, 401 insertions(+)
>  create mode 100644 drivers/pwm/pwm-mc33xs2410.c
> 
> diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> index 0915c1e7df16..f513513f9b2f 100644
> --- a/drivers/pwm/Kconfig
> +++ b/drivers/pwm/Kconfig
> @@ -411,6 +411,18 @@ config PWM_LPSS_PLATFORM
>  	  To compile this driver as a module, choose M here: the module
>  	  will be called pwm-lpss-platform.
>  
> +config PWM_MC33XS2410
> +	tristate "MC33XS2410 PWM support"
> +	depends on OF
> +	depends on SPI
> +	help
> +	  NXP MC33XS2410 high-side switch driver. The MC33XS2410 is a four
> +	  channel high-side switch. The device is operational from 3.0 V
> +	  to 60 V. The device is controlled by SPI port for configuration.
> +
> +	  To compile this driver as a module, choose M here: the module
> +	  will be called pwm-mc33xs2410.
> +
>  config PWM_MESON
>  	tristate "Amlogic Meson PWM driver"
>  	depends on ARCH_MESON || COMPILE_TEST
> diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> index 9081e0c0e9e0..c75deeeace40 100644
> --- a/drivers/pwm/Makefile
> +++ b/drivers/pwm/Makefile
> @@ -36,6 +36,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
>  obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
>  obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
>  obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
> +obj-$(CONFIG_PWM_MC33XS2410)	+= pwm-mc33xs2410.o
>  obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
>  obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
>  obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
> diff --git a/drivers/pwm/pwm-mc33xs2410.c b/drivers/pwm/pwm-mc33xs2410.c
> new file mode 100644
> index 000000000000..97cf31ef608a
> --- /dev/null
> +++ b/drivers/pwm/pwm-mc33xs2410.c
> @@ -0,0 +1,388 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Copyright (C) 2024 Liebherr-Electronics and Drives GmbH
> + *
> + * Reference Manual : https://www.nxp.com/docs/en/data-sheet/MC33XS2410.pdf
> + *
> + * Limitations:
> + * - Supports frequencies between 0.5Hz and 2048Hz with following steps:
> + *   - 0.5 Hz steps from 0.5 Hz to 32 Hz
> + *   - 2 Hz steps from 2 Hz to 128 Hz
> + *   - 8 Hz steps from 8 Hz to 512 Hz
> + *   - 32 Hz steps from 32 Hz to 2048 Hz
> + * - Cannot generate a 0 % duty cycle.
> + * - Always produces low output if disabled.
> + * - Configuration isn't atomic. When changing polarity, duty cycle or period
> + *   the data is taken immediately, counters not being affected, resulting in a
> + *   behavior of the output pin that is neither the old nor the new state,
> + *   rather something in between.
> + */
> +
> +#include <linux/bitfield.h>
> +#include <linux/delay.h>
> +#include <linux/err.h>
> +#include <linux/math64.h>
> +#include <linux/minmax.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/pwm.h>
> +
> +#include <linux/spi/spi.h>
> +
> +#define MC33XS2410_GLB_CTRL		0x00
> +#define MC33XS2410_GLB_CTRL_MODE	GENMASK(7, 6)
> +#define MC33XS2410_GLB_CTRL_MODE_NORMAL	FIELD_PREP(MC33XS2410_GLB_CTRL_MODE, 1)
> +
> +#define MC33XS2410_PWM_CTRL1		0x05
> +/* x in { 1 ... 4 } */

Here x ranges over the 4 output channels, right? Maybe call it "chan" or
similar instead of "x"?

> +#define MC33XS2410_PWM_CTRL1_POL_INV(x)	BIT((x - 1))

BIT((x) - 1)

> +
> +#define MC33XS2410_PWM_CTRL3		0x07
> +/* x in { 1 ... 4 } */
> +#define MC33XS2410_PWM_CTRL3_EN(x)	BIT(4 + (x - 1))
> +
> +/* x in { 1 ... 4 } */
> +#define MC33XS2410_PWM_FREQ(x)		(0x08 + (x - 1))
> +#define MC33XS2410_PWM_FREQ_STEP	GENMASK(7, 6)
> +#define MC33XS2410_PWM_FREQ_COUNT	GENMASK(5, 0)
> +
> +/* x in { 1 ... 4 } */
> +#define MC33XS2410_PWM_DC(x)		(0x0c + (x - 1))
> +
> +#define MC33XS2410_WDT			0x14
> +
> +#define MC33XS2410_PWM_MIN_PERIOD	488282
> +/* x in { 0 ... 3 } */
> +#define MC33XS2410_PWM_MAX_PERIOD(x)	(2000000000 >> (2 * x))

Here x ranges over the four period intervals. I suggest to call this x
"step" instead. Also the parameter needs bracketing.

> +#define MC33XS2410_FRAME_IN_ADDR	GENMASK(15, 8)
> +#define MC33XS2410_FRAME_IN_DATA	GENMASK(7, 0)
> +#define MC33XS2410_FRAME_IN_ADDR_WR	BIT(7)
> +#define MC33XS2410_FRAME_IN_DATA_RD	BIT(7)
> +#define MC33XS2410_FRAME_OUT_DATA	GENMASK(13, 0)
> +
> +#define MC33XS2410_MAX_TRANSFERS	5
> +
> [...]
> +static int mc33xs2410_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> +				const struct pwm_state *state)
> +{
> +	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
> +	struct spi_device *spi = mc33xs2410->spi;
> +	u8 reg[4] = {
> +			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
> +			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
> +			MC33XS2410_PWM_CTRL1,
> +			MC33XS2410_PWM_CTRL3
> +		    };
> +	u64 period, duty_cycle;
> +	int ret, rel_dc;
> +	u16 rd_val[2];
> +	u8 wr_val[4];
> +	u8 mask;
> +
> +	period = min(state->period, MC33XS2410_PWM_MAX_PERIOD(0));
> +	if (period < MC33XS2410_PWM_MIN_PERIOD)
> +		return -EINVAL;
> +
> +	ret = mc33xs2410_read_regs(spi, &reg[2], MC33XS2410_FRAME_IN_DATA_RD, rd_val, 2);
> +	if (ret < 0)
> +		return ret;
> +
> +	/* frequency */
> +	wr_val[0] = mc33xs2410_pwm_get_freq(period);
> +	/* Continue calculations with the possibly truncated period */
> +	period = mc33xs2410_pwm_get_period(wr_val[0]);
> +
> +	/* duty cycle */
> +	duty_cycle = min(period, state->duty_cycle);
> +	rel_dc = div64_u64(duty_cycle * 256, period) - 1;
> +	if (rel_dc < 0)
> +		wr_val[1] = 0;
> +	else
> +		wr_val[1] = rel_dc;
> +
> +	/* polarity */
> +	mask = MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm + 1);
> +	wr_val[2] = (state->polarity == PWM_POLARITY_INVERSED) ?
> +		    (rd_val[0] | mask) : (rd_val[0] & ~mask);
> +
> +	/* enable output */

/*
 * As the hardware cannot generate a 0% relative duty cycle but emits a
 * constant low signal when disabled, also disable in the duty_cycle = 0
 * case.
 */

> +	mask = MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm + 1);
> +	wr_val[3] = (state->enabled && rel_dc >= 0) ? (rd_val[1] | mask) :
> +						      (rd_val[1] & ~mask);
> +
> +	return mc33xs2410_write_regs(spi, reg, wr_val, 4);
> +}
> +
> +static int mc33xs2410_pwm_get_state(struct pwm_chip *chip,
> +				    struct pwm_device *pwm,
> +				    struct pwm_state *state)
> +{
> +	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
> +	struct spi_device *spi = mc33xs2410->spi;
> +	u8 reg[4] = {
> +			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
> +			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
> +			MC33XS2410_PWM_CTRL1,
> +			MC33XS2410_PWM_CTRL3,
> +		    };
> +	u16 val[4];
> +	int ret;
> +
> +	ret = mc33xs2410_read_regs(spi, reg, MC33XS2410_FRAME_IN_DATA_RD, val, 4);

ARRAY_SIZE(reg) instead of hardcoded 4?

> +	if (ret < 0)
> +		return ret;
> +
> +	state->period = mc33xs2410_pwm_get_period(val[0]);
> +	state->polarity = (val[2] & MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm + 1)) ?
> +			  PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
> +	state->enabled = !!(val[3] & MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm + 1));
> +	state->duty_cycle = DIV_ROUND_UP_ULL((val[1] + 1) * state->period, 256);
> +
> +	return 0;
> +}
> [...]
> +static int mc33xs2410_probe(struct spi_device *spi)
> +{
> +	struct mc33xs2410_pwm *mc33xs2410;
> +	struct device *dev = &spi->dev;
> +	struct pwm_chip *chip;
> +	int ret;
> +
> +	chip = devm_pwmchip_alloc(dev, 4, sizeof(*mc33xs2410));
> +	if (IS_ERR(chip))
> +		return PTR_ERR(chip);
> +
> +	spi->bits_per_word = 16;
> +	spi->mode |= SPI_CS_WORD;
> +	ret = spi_setup(spi);
> +	if (ret < 0)
> +		return ret;
> +
> +	mc33xs2410 = mc33xs2410_from_chip(chip);
> +	mc33xs2410->spi = spi;
> +	chip->ops = &mc33xs2410_pwm_ops;

Given that struct mc33xs2410_pwm only has a single member you can pass 0
as 3rd parameter to devm_pwmchip_alloc(), call pwmchip_set_drvdata(chip,
spi). Then you can save on indirection.

> +	ret = mc33xs2410_reset(dev);
> +	if (ret)
> +		return ret;
> +

Best regards
Uwe

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Re: [PATCH v7 2/2] pwm: add support for NXPs high-side switch MC33XS2410

[Dimitri Fedrau]

Hello Uwe,

Am Wed, Jan 08, 2025 at 09:01:07AM +0100 schrieb Uwe Kleine-König:
> Hello Dimitri,
> 
> thanks for your patience. I'm mostly happy now. Just a few minor
> comments below:
> 
> On Sat, Nov 09, 2024 at 06:41:35PM +0100, Dimitri Fedrau wrote:
> > The MC33XS2410 is a four channel high-side switch. Featuring advanced
> > monitoring and control function, the device is operational from 3.0 V to
> > 60 V. The device is controlled by SPI port for configuration.
> > 
> > Signed-off-by: Dimitri Fedrau <dima.fedrau@gmail.com>
> > ---
> >  drivers/pwm/Kconfig          |  12 ++
> >  drivers/pwm/Makefile         |   1 +
> >  drivers/pwm/pwm-mc33xs2410.c | 388 +++++++++++++++++++++++++++++++++++
> >  3 files changed, 401 insertions(+)
> >  create mode 100644 drivers/pwm/pwm-mc33xs2410.c
> > 
> > diff --git a/drivers/pwm/Kconfig b/drivers/pwm/Kconfig
> > index 0915c1e7df16..f513513f9b2f 100644
> > --- a/drivers/pwm/Kconfig
> > +++ b/drivers/pwm/Kconfig
> > @@ -411,6 +411,18 @@ config PWM_LPSS_PLATFORM
> >  	  To compile this driver as a module, choose M here: the module
> >  	  will be called pwm-lpss-platform.
> >  
> > +config PWM_MC33XS2410
> > +	tristate "MC33XS2410 PWM support"
> > +	depends on OF
> > +	depends on SPI
> > +	help
> > +	  NXP MC33XS2410 high-side switch driver. The MC33XS2410 is a four
> > +	  channel high-side switch. The device is operational from 3.0 V
> > +	  to 60 V. The device is controlled by SPI port for configuration.
> > +
> > +	  To compile this driver as a module, choose M here: the module
> > +	  will be called pwm-mc33xs2410.
> > +
> >  config PWM_MESON
> >  	tristate "Amlogic Meson PWM driver"
> >  	depends on ARCH_MESON || COMPILE_TEST
> > diff --git a/drivers/pwm/Makefile b/drivers/pwm/Makefile
> > index 9081e0c0e9e0..c75deeeace40 100644
> > --- a/drivers/pwm/Makefile
> > +++ b/drivers/pwm/Makefile
> > @@ -36,6 +36,7 @@ obj-$(CONFIG_PWM_LPC32XX)	+= pwm-lpc32xx.o
> >  obj-$(CONFIG_PWM_LPSS)		+= pwm-lpss.o
> >  obj-$(CONFIG_PWM_LPSS_PCI)	+= pwm-lpss-pci.o
> >  obj-$(CONFIG_PWM_LPSS_PLATFORM)	+= pwm-lpss-platform.o
> > +obj-$(CONFIG_PWM_MC33XS2410)	+= pwm-mc33xs2410.o
> >  obj-$(CONFIG_PWM_MESON)		+= pwm-meson.o
> >  obj-$(CONFIG_PWM_MEDIATEK)	+= pwm-mediatek.o
> >  obj-$(CONFIG_PWM_MICROCHIP_CORE)	+= pwm-microchip-core.o
> > diff --git a/drivers/pwm/pwm-mc33xs2410.c b/drivers/pwm/pwm-mc33xs2410.c
> > new file mode 100644
> > index 000000000000..97cf31ef608a
> > --- /dev/null
> > +++ b/drivers/pwm/pwm-mc33xs2410.c
> > @@ -0,0 +1,388 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/*
> > + * Copyright (C) 2024 Liebherr-Electronics and Drives GmbH
> > + *
> > + * Reference Manual : https://www.nxp.com/docs/en/data-sheet/MC33XS2410.pdf
> > + *
> > + * Limitations:
> > + * - Supports frequencies between 0.5Hz and 2048Hz with following steps:
> > + *   - 0.5 Hz steps from 0.5 Hz to 32 Hz
> > + *   - 2 Hz steps from 2 Hz to 128 Hz
> > + *   - 8 Hz steps from 8 Hz to 512 Hz
> > + *   - 32 Hz steps from 32 Hz to 2048 Hz
> > + * - Cannot generate a 0 % duty cycle.
> > + * - Always produces low output if disabled.
> > + * - Configuration isn't atomic. When changing polarity, duty cycle or period
> > + *   the data is taken immediately, counters not being affected, resulting in a
> > + *   behavior of the output pin that is neither the old nor the new state,
> > + *   rather something in between.
> > + */
> > +
> > +#include <linux/bitfield.h>
> > +#include <linux/delay.h>
> > +#include <linux/err.h>
> > +#include <linux/math64.h>
> > +#include <linux/minmax.h>
> > +#include <linux/module.h>
> > +#include <linux/of.h>
> > +#include <linux/pwm.h>
> > +
> > +#include <linux/spi/spi.h>
> > +
> > +#define MC33XS2410_GLB_CTRL		0x00
> > +#define MC33XS2410_GLB_CTRL_MODE	GENMASK(7, 6)
> > +#define MC33XS2410_GLB_CTRL_MODE_NORMAL	FIELD_PREP(MC33XS2410_GLB_CTRL_MODE, 1)
> > +
> > +#define MC33XS2410_PWM_CTRL1		0x05
> > +/* x in { 1 ... 4 } */
> 
> Here x ranges over the 4 output channels, right? Maybe call it "chan" or
> similar instead of "x"?
> 
I will call it chan and do the same for MC33XS2410_PWM_CTRL3_EN,
MC33XS2410_PWM_FREQ and MC33XS2410_PWM_DC.

> > +#define MC33XS2410_PWM_CTRL1_POL_INV(x)	BIT((x - 1))
> 
> BIT((x) - 1)
> 
Will fix it for others too.

> > +
> > +#define MC33XS2410_PWM_CTRL3		0x07
> > +/* x in { 1 ... 4 } */
> > +#define MC33XS2410_PWM_CTRL3_EN(x)	BIT(4 + (x - 1))
> > +
> > +/* x in { 1 ... 4 } */
> > +#define MC33XS2410_PWM_FREQ(x)		(0x08 + (x - 1))
> > +#define MC33XS2410_PWM_FREQ_STEP	GENMASK(7, 6)
> > +#define MC33XS2410_PWM_FREQ_COUNT	GENMASK(5, 0)
> > +
> > +/* x in { 1 ... 4 } */
> > +#define MC33XS2410_PWM_DC(x)		(0x0c + (x - 1))
> > +
> > +#define MC33XS2410_WDT			0x14
> > +
> > +#define MC33XS2410_PWM_MIN_PERIOD	488282
> > +/* x in { 0 ... 3 } */
> > +#define MC33XS2410_PWM_MAX_PERIOD(x)	(2000000000 >> (2 * x))
> 
> Here x ranges over the four period intervals. I suggest to call this x
> "step" instead. Also the parameter needs bracketing.
> 
Ok.

> > +#define MC33XS2410_FRAME_IN_ADDR	GENMASK(15, 8)
> > +#define MC33XS2410_FRAME_IN_DATA	GENMASK(7, 0)
> > +#define MC33XS2410_FRAME_IN_ADDR_WR	BIT(7)
> > +#define MC33XS2410_FRAME_IN_DATA_RD	BIT(7)
> > +#define MC33XS2410_FRAME_OUT_DATA	GENMASK(13, 0)
> > +
> > +#define MC33XS2410_MAX_TRANSFERS	5
> > +
> > [...]
> > +static int mc33xs2410_pwm_apply(struct pwm_chip *chip, struct pwm_device *pwm,
> > +				const struct pwm_state *state)
> > +{
> > +	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
> > +	struct spi_device *spi = mc33xs2410->spi;
> > +	u8 reg[4] = {
> > +			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
> > +			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
> > +			MC33XS2410_PWM_CTRL1,
> > +			MC33XS2410_PWM_CTRL3
> > +		    };
> > +	u64 period, duty_cycle;
> > +	int ret, rel_dc;
> > +	u16 rd_val[2];
> > +	u8 wr_val[4];
> > +	u8 mask;
> > +
> > +	period = min(state->period, MC33XS2410_PWM_MAX_PERIOD(0));
> > +	if (period < MC33XS2410_PWM_MIN_PERIOD)
> > +		return -EINVAL;
> > +
> > +	ret = mc33xs2410_read_regs(spi, &reg[2], MC33XS2410_FRAME_IN_DATA_RD, rd_val, 2);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	/* frequency */
> > +	wr_val[0] = mc33xs2410_pwm_get_freq(period);
> > +	/* Continue calculations with the possibly truncated period */
> > +	period = mc33xs2410_pwm_get_period(wr_val[0]);
> > +
> > +	/* duty cycle */
> > +	duty_cycle = min(period, state->duty_cycle);
> > +	rel_dc = div64_u64(duty_cycle * 256, period) - 1;
> > +	if (rel_dc < 0)
> > +		wr_val[1] = 0;
> > +	else
> > +		wr_val[1] = rel_dc;
> > +
> > +	/* polarity */
> > +	mask = MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm + 1);
> > +	wr_val[2] = (state->polarity == PWM_POLARITY_INVERSED) ?
> > +		    (rd_val[0] | mask) : (rd_val[0] & ~mask);
> > +
> > +	/* enable output */
> 
> /*
>  * As the hardware cannot generate a 0% relative duty cycle but emits a
>  * constant low signal when disabled, also disable in the duty_cycle = 0
>  * case.
>  */
>
Will add the comment as is, thanks.

> > +	mask = MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm + 1);
> > +	wr_val[3] = (state->enabled && rel_dc >= 0) ? (rd_val[1] | mask) :
> > +						      (rd_val[1] & ~mask);
> > +
> > +	return mc33xs2410_write_regs(spi, reg, wr_val, 4);
> > +}
> > +
> > +static int mc33xs2410_pwm_get_state(struct pwm_chip *chip,
> > +				    struct pwm_device *pwm,
> > +				    struct pwm_state *state)
> > +{
> > +	struct mc33xs2410_pwm *mc33xs2410 = mc33xs2410_from_chip(chip);
> > +	struct spi_device *spi = mc33xs2410->spi;
> > +	u8 reg[4] = {
> > +			MC33XS2410_PWM_FREQ(pwm->hwpwm + 1),
> > +			MC33XS2410_PWM_DC(pwm->hwpwm + 1),
> > +			MC33XS2410_PWM_CTRL1,
> > +			MC33XS2410_PWM_CTRL3,
> > +		    };
> > +	u16 val[4];
> > +	int ret;
> > +
> > +	ret = mc33xs2410_read_regs(spi, reg, MC33XS2410_FRAME_IN_DATA_RD, val, 4);
> 
> ARRAY_SIZE(reg) instead of hardcoded 4?
>
I'm not sure, but I can change it.

> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	state->period = mc33xs2410_pwm_get_period(val[0]);
> > +	state->polarity = (val[2] & MC33XS2410_PWM_CTRL1_POL_INV(pwm->hwpwm + 1)) ?
> > +			  PWM_POLARITY_INVERSED : PWM_POLARITY_NORMAL;
> > +	state->enabled = !!(val[3] & MC33XS2410_PWM_CTRL3_EN(pwm->hwpwm + 1));
> > +	state->duty_cycle = DIV_ROUND_UP_ULL((val[1] + 1) * state->period, 256);
> > +
> > +	return 0;
> > +}
> > [...]
> > +static int mc33xs2410_probe(struct spi_device *spi)
> > +{
> > +	struct mc33xs2410_pwm *mc33xs2410;
> > +	struct device *dev = &spi->dev;
> > +	struct pwm_chip *chip;
> > +	int ret;
> > +
> > +	chip = devm_pwmchip_alloc(dev, 4, sizeof(*mc33xs2410));
> > +	if (IS_ERR(chip))
> > +		return PTR_ERR(chip);
> > +
> > +	spi->bits_per_word = 16;
> > +	spi->mode |= SPI_CS_WORD;
> > +	ret = spi_setup(spi);
> > +	if (ret < 0)
> > +		return ret;
> > +
> > +	mc33xs2410 = mc33xs2410_from_chip(chip);
> > +	mc33xs2410->spi = spi;
> > +	chip->ops = &mc33xs2410_pwm_ops;
> 
> Given that struct mc33xs2410_pwm only has a single member you can pass 0
> as 3rd parameter to devm_pwmchip_alloc(), call pwmchip_set_drvdata(chip,
> spi). Then you can save on indirection.
> 
Yes, that makes sense.

> > +	ret = mc33xs2410_reset(dev);
> > +	if (ret)
> > +		return ret;
> > +
> 
Best regards,
Dimitri