pwm: mc33xs2410: add hwmon support

Support for hwmon is provided by a separate driver residing in hwmon
subsystem which is implemented as auxiliary device. Add handling of this
device.

Signed-off-by: Dimitri Fedrau <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Uwe Kleine-König <[e-mail]>

drivers/pwm/Kconfig

···
 	tristate "MC33XS2410 PWM support"
 	depends on OF
 	depends on SPI
+	select AUXILIARY_BUS
 	help
 	  NXP MC33XS2410 high-side switch driver. The MC33XS2410 is a four
 	  channel high-side switch. The device is operational from 3.0 V

drivers/pwm/pwm-mc33xs2410.c

···
  *   behavior of the output pin that is neither the old nor the new state,
  *   rather something in between.
  */
+#define DEFAULT_SYMBOL_NAMESPACE		"PWM_MC33XS2410"
 
+#include <linux/auxiliary_bus.h>
 #include <linux/bitfield.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/math64.h>
+#include <linux/mc33xs2410.h>
 #include <linux/minmax.h>
 #include <linux/module.h>
 #include <linux/of.h>
···
 	return mc33xs2410_read_regs(spi, &reg, flag, val, 1);
 }
 
-static int mc33xs2410_read_reg_ctrl(struct spi_device *spi, u8 reg, u16 *val)
+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);
 }
+EXPORT_SYMBOL_GPL(mc33xs2410_read_reg_ctrl);
 
-static int mc33xs2410_modify_reg(struct spi_device *spi, u8 reg, u8 mask, u8 val)
+int mc33xs2410_read_reg_diag(struct spi_device *spi, u8 reg, u16 *val)
+{
+	return mc33xs2410_read_reg(spi, reg, val, 0);
+}
+EXPORT_SYMBOL_GPL(mc33xs2410_read_reg_diag);
+
+int mc33xs2410_modify_reg(struct spi_device *spi, u8 reg, u8 mask, u8 val)
 {
 	u16 tmp;
 	int ret;
···
 
 	return mc33xs2410_write_reg(spi, reg, tmp);
 }
+EXPORT_SYMBOL_GPL(mc33xs2410_modify_reg);
 
 static u8 mc33xs2410_pwm_get_freq(u64 period)
 {
···
 static int mc33xs2410_probe(struct spi_device *spi)
 {
 	struct device *dev = &spi->dev;
+	struct auxiliary_device *adev;
 	struct pwm_chip *chip;
 	int ret;
 
···
 	ret = devm_pwmchip_add(dev, chip);
 	if (ret < 0)
 		return dev_err_probe(dev, ret, "Failed to add pwm chip\n");
+
+	adev = devm_auxiliary_device_create(dev, "hwmon", NULL);
+	if (!adev)
+		return dev_err_probe(dev, -ENODEV, "Failed to register hwmon device\n");
 
 	return 0;
 }

include/linux/mc33xs2410.h

···
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2024 Liebherr-Electronics and Drives GmbH
+ */
+#ifndef _MC33XS2410_H
+#define _MC33XS2410_H
+
+#include <linux/spi/spi.h>
+
+MODULE_IMPORT_NS("PWM_MC33XS2410");
+
+int mc33xs2410_read_reg_ctrl(struct spi_device *spi, u8 reg, u16 *val);
+int mc33xs2410_read_reg_diag(struct spi_device *spi, u8 reg, u16 *val);
+int mc33xs2410_modify_reg(struct spi_device *spi, u8 reg, u8 mask, u8 val);
+
+#endif /* _MC33XS2410_H */