pinctrl: pinctrl-single: fix pcs_pin_dbg_show() when bits_per_mux is not zero

A System Error (SError, followed by kernel panic) was detected when
trying to print the supported pins in a pinctrl device which supports
multiple pins per register. This change fixes the pcs_pin_dbg_show() in
pinctrl-single driver when bits_per_mux is not zero. In addition move
offset calculation and pin offset in register to common function.

Fixes: 4e7e8017 ("pinctrl: pinctrl-single: enhance to configure multiple pins of different modules")
Signed-off-by: Hanna Hawa <hhhawa@amazon.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Reviewed-by: Tony Lindgren <tony@atomide.com>
Reviewed-by: Drew Fustini <drew@beagleboard.org>
Link: https://lore.kernel.org/r/20210319152133.28705-4-hhhawa@amazon.comSigned-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-single.c

@@ -270,20 +270,44 @@ static void __maybe_unused pcs_writel(unsigned val, void __iomem *reg)
 	writel(val, reg);
 }
 
+static unsigned int pcs_pin_reg_offset_get(struct pcs_device *pcs,
+					   unsigned int pin)
+{
+	unsigned int mux_bytes = pcs->width / BITS_PER_BYTE;
+
+	if (pcs->bits_per_mux) {
+		unsigned int pin_offset_bytes;
+
+		pin_offset_bytes = (pcs->bits_per_pin * pin) / BITS_PER_BYTE;
+		return (pin_offset_bytes / mux_bytes) * mux_bytes;
+	}
+
+	return pin * mux_bytes;
+}
+
+static unsigned int pcs_pin_shift_reg_get(struct pcs_device *pcs,
+					  unsigned int pin)
+{
+	return (pin % (pcs->width / pcs->bits_per_pin)) * pcs->bits_per_pin;
+}
+
 static void pcs_pin_dbg_show(struct pinctrl_dev *pctldev,
 					struct seq_file *s,
 					unsigned pin)
 {
 	struct pcs_device *pcs;
-	unsigned val, mux_bytes;
+	unsigned int val;
 	unsigned long offset;
 	size_t pa;
 
 	pcs = pinctrl_dev_get_drvdata(pctldev);
 
-	mux_bytes = pcs->width / BITS_PER_BYTE;
-	offset = pin * mux_bytes;
+	offset = pcs_pin_reg_offset_get(pcs, pin);
 	val = pcs->read(pcs->base + offset);
+
+	if (pcs->bits_per_mux)
+		val &= pcs->fmask << pcs_pin_shift_reg_get(pcs, pin);
+
 	pa = pcs->res->start + offset;
 
 	seq_printf(s, "%zx %08x %s ", pa, val, DRIVER_NAME);
@@ -384,7 +408,6 @@ static int pcs_request_gpio(struct pinctrl_dev *pctldev,
 	struct pcs_device *pcs = pinctrl_dev_get_drvdata(pctldev);
 	struct pcs_gpiofunc_range *frange = NULL;
 	struct list_head *pos, *tmp;
-	int mux_bytes = 0;
 	unsigned data;
 
 	/* If function mask is null, return directly. */
@@ -392,29 +415,27 @@ static int pcs_request_gpio(struct pinctrl_dev *pctldev,
 		return -ENOTSUPP;
 
 	list_for_each_safe(pos, tmp, &pcs->gpiofuncs) {
+		u32 offset;
+
 		frange = list_entry(pos, struct pcs_gpiofunc_range, node);
 		if (pin >= frange->offset + frange->npins
 			|| pin < frange->offset)
 			continue;
-		mux_bytes = pcs->width / BITS_PER_BYTE;
 
-		if (pcs->bits_per_mux) {
-			int byte_num, offset, pin_shift;
+		offset = pcs_pin_reg_offset_get(pcs, pin);
 
-			byte_num = (pcs->bits_per_pin * pin) / BITS_PER_BYTE;
-			offset = (byte_num / mux_bytes) * mux_bytes;
-			pin_shift = pin % (pcs->width / pcs->bits_per_pin) *
-				    pcs->bits_per_pin;
+		if (pcs->bits_per_mux) {
+			int pin_shift = pcs_pin_shift_reg_get(pcs, pin);
 
 			data = pcs->read(pcs->base + offset);
 			data &= ~(pcs->fmask << pin_shift);
 			data |= frange->gpiofunc << pin_shift;
 			pcs->write(data, pcs->base + offset);
 		} else {
-			data = pcs->read(pcs->base + pin * mux_bytes);
+			data = pcs->read(pcs->base + offset);
 			data &= ~pcs->fmask;
 			data |= frange->gpiofunc;
-			pcs->write(data, pcs->base + pin * mux_bytes);
+			pcs->write(data, pcs->base + offset);
 		}
 		break;
 	}
@@ -724,14 +745,8 @@ static int pcs_allocate_pin_table(struct pcs_device *pcs)
 	for (i = 0; i < pcs->desc.npins; i++) {
 		unsigned offset;
 		int res;
-		int byte_num;
 
-		if (pcs->bits_per_mux) {
-			byte_num = (pcs->bits_per_pin * i) / BITS_PER_BYTE;
-			offset = (byte_num / mux_bytes) * mux_bytes;
-		} else {
-			offset = i * mux_bytes;
-		}
+		offset = pcs_pin_reg_offset_get(pcs, i);
 		res = pcs_add_pin(pcs, offset);
 		if (res < 0) {
 			dev_err(pcs->dev, "error adding pins: %i\n", res);