pwm: Add the S32G support in the Freescale FTM driver

The Automotive S32G2 and S32G3 platforms include two FTM timers for
pwm. Each FTM has 6 PWM channels.

The current Freescale FTM driver supports the iMX8 and the Vybrid
Family FTM IP. The FTM IP found on the S32G platforms is almost
identical except for the number of channels and the register mapping.

These changes allow to deal with different number of channels and
support the holes found in the register memory mapping for s32gx for
suspend / resume. The fault register does not exist on the s32gx and
at resume time all the mapping is wrote back leading to a kernel
crash.

/* restore all registers from cache */
regcache_cache_only(fpc->regmap, false);
regcache_sync(fpc->regmap);

The regmap callbacks 'writeable_reg()' and 'readable_reg()' will skip
the address corresponding to a register which is not present.

Tested on a s32g274-rdb2 J5 PWM pin output with signal visualization
on oscilloscope.

Signed-off-by: Ghennadi Procopciuc <[e-mail]>
Co-developed-by: Daniel Lezcano <[e-mail]>
Signed-off-by: Daniel Lezcano <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Uwe Kleine-König <[e-mail]>

drivers/pwm/pwm-fsl-ftm.c

···
  *  Freescale FlexTimer Module (FTM) PWM Driver
  *
  *  Copyright 2012-2013 Freescale Semiconductor, Inc.
+ *  Copyright 2020-2025 NXP
  */
 
 #include <linux/clk.h>
···
 
 struct fsl_ftm_soc {
 	bool has_enable_bits;
+	bool has_flt_reg;
+	unsigned int npwm;
 };
 
 struct fsl_pwm_periodcfg {
···
 	return false;
 }
 
+static bool fsl_pwm_is_reg(struct device *dev, unsigned int reg)
+{
+	struct pwm_chip *chip = dev_get_drvdata(dev);
+	struct fsl_pwm_chip *fpc = to_fsl_chip(chip);
+
+	if (reg >= FTM_CSC(fpc->soc->npwm) && reg < FTM_CNTIN)
+		return false;
+
+	if ((reg == FTM_FLTCTRL || reg == FTM_FLTPOL) && !fpc->soc->has_flt_reg)
+		return false;
+
+	return true;
+}
+
 static const struct regmap_config fsl_pwm_regmap_config = {
 	.reg_bits = 32,
 	.reg_stride = 4,
···
 	.max_register = FTM_PWMLOAD,
 	.volatile_reg = fsl_pwm_volatile_reg,
 	.cache_type = REGCACHE_FLAT,
+	.writeable_reg = fsl_pwm_is_reg,
+	.readable_reg = fsl_pwm_is_reg,
 };
 
 static int fsl_pwm_probe(struct platform_device *pdev)
 {
+	const struct fsl_ftm_soc *soc = of_device_get_match_data(&pdev->dev);
 	struct pwm_chip *chip;
 	struct fsl_pwm_chip *fpc;
 	void __iomem *base;
 	int ret;
 
-	chip = devm_pwmchip_alloc(&pdev->dev, 8, sizeof(*fpc));
+	chip = devm_pwmchip_alloc(&pdev->dev, soc->npwm, sizeof(*fpc));
 	if (IS_ERR(chip))
 		return PTR_ERR(chip);
 	fpc = to_fsl_chip(chip);
 
-	fpc->soc = of_device_get_match_data(&pdev->dev);
+	fpc->soc = soc;
 
 	base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(base))
···
 
 static const struct fsl_ftm_soc vf610_ftm_pwm = {
 	.has_enable_bits = false,
+	.has_flt_reg = true,
+	.npwm = 8,
 };
 
 static const struct fsl_ftm_soc imx8qm_ftm_pwm = {
 	.has_enable_bits = true,
+	.has_flt_reg = true,
+	.npwm = 8,
+};
+
+static const struct fsl_ftm_soc s32g2_ftm_pwm = {
+	.has_enable_bits = true,
+	.has_flt_reg = false,
+	.npwm = 6,
 };
 
 static const struct of_device_id fsl_pwm_dt_ids[] = {
 	{ .compatible = "fsl,vf610-ftm-pwm", .data = &vf610_ftm_pwm },
 	{ .compatible = "fsl,imx8qm-ftm-pwm", .data = &imx8qm_ftm_pwm },
+	{ .compatible = "nxp,s32g2-ftm-pwm", .data = &s32g2_ftm_pwm },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, fsl_pwm_dt_ids);