pinctrl: at91-pio4: add support for fewer lines on last PIO bank

Some products, like sama7g5, do not have a full last bank of PIO lines.
In this case for example, sama7g5 only has 8 lines for the PE bank.
PA0-31, PB0-31, PC0-31, PD0-31, PE0-7, in total 136 lines.
To cope with this situation, added a data attribute that is product dependent,
to specify the number of lines of the last bank.
In case this number is different from the macro ATMEL_PIO_NPINS_PER_BANK,
adjust the total number of lines accordingly.
This will avoid advertising 160 lines instead of the actual 136, as this
product supports, and to avoid reading/writing to invalid register addresses.

Signed-off-by: Eugen Hristev <eugen.hristev@microchip.com>
Acked-by: Ludovic Desroches <ludovic.desroches@microchip.com>
Link: https://lore.kernel.org/r/20201113132429.420940-1-eugen.hristev@microchip.com
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

drivers/pinctrl/pinctrl-at91-pio4.c

@@ -71,8 +71,15 @@
 /* Custom pinconf parameters */
 #define ATMEL_PIN_CONFIG_DRIVE_STRENGTH	(PIN_CONFIG_END + 1)
 
+/**
+ * struct atmel_pioctrl_data - Atmel PIO controller (pinmux + gpio) data struct
+ * @nbanks: number of PIO banks
+ * @last_bank_count: number of lines in the last bank (can be less than
+ *	the rest of the banks).
+ */
 struct atmel_pioctrl_data {
 	unsigned nbanks;
+	unsigned last_bank_count;
 };
 
 struct atmel_group {
@@ -980,11 +987,13 @@ static const struct dev_pm_ops atmel_pctrl_pm_ops = {
  * We can have up to 16 banks.
  */
 static const struct atmel_pioctrl_data atmel_sama5d2_pioctrl_data = {
-	.nbanks		= 4,
+	.nbanks			= 4,
+	.last_bank_count	= ATMEL_PIO_NPINS_PER_BANK,
 };
 
 static const struct atmel_pioctrl_data microchip_sama7g5_pioctrl_data = {
-	.nbanks		= 5,
+	.nbanks			= 5,
+	.last_bank_count	= 8, /* sama7g5 has only PE0 to PE7 */
 };
 
 static const struct of_device_id atmel_pctrl_of_match[] = {
@@ -1025,6 +1034,11 @@ static int atmel_pinctrl_probe(struct platform_device *pdev)
 	atmel_pioctrl_data = match->data;
 	atmel_pioctrl->nbanks = atmel_pioctrl_data->nbanks;
 	atmel_pioctrl->npins = atmel_pioctrl->nbanks * ATMEL_PIO_NPINS_PER_BANK;
+	/* if last bank has limited number of pins, adjust accordingly */
+	if (atmel_pioctrl_data->last_bank_count != ATMEL_PIO_NPINS_PER_BANK) {
+		atmel_pioctrl->npins -= ATMEL_PIO_NPINS_PER_BANK;
+		atmel_pioctrl->npins += atmel_pioctrl_data->last_bank_count;
+	}
 
 	atmel_pioctrl->reg_base = devm_platform_ioremap_resource(pdev, 0);
 	if (IS_ERR(atmel_pioctrl->reg_base))