pinctrl/nomadik: support other alternate-C functions

Upgrade nomadik pinctrl driver to enable selection of other
alternate-C[1-4] functions on some specific ux500 SoC pins.
Handling of those functions is done thanks to PRCM GPIOCR
registers. This was previously managed in PRCMU driver and
it was not really convenient. Idea is to provide a common
way to control all alternate functions.

Note that this improvement does not support the old-fashioned way
used to control nomadik pins, namely the "nmk_config_pin()" function
and its derivatives.

Signed-off-by: Jean-Nicolas Graux <jean-nicolas.graux@stericsson.com>
Reviewed-by: Philippe Langlais <philippe.langlais@stericsson.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

1 files changed, 99 insertions, 2 deletions

diff --git a/drivers/pinctrl/pinctrl-nomadik.c b/drivers/pinctrl/pinctrl-nomadik.c
index 6030a513f3c4..67a5ef637ea7 100644
--- a/drivers/pinctrl/pinctrl-nomadik.c
+++ b/drivers/pinctrl/pinctrl-nomadik.c
@@ -30,6 +30,7 @@
 #include <linux/pinctrl/pinconf.h>
 /* Since we request GPIOs from ourself */
 #include <linux/pinctrl/consumer.h>
+#include <linux/mfd/dbx500-prcmu.h>
 
 #include <asm/mach/irq.h>
 
@@ -237,6 +238,89 @@ nmk_gpio_disable_lazy_irq(struct nmk_gpio_chip *nmk_chip, unsigned offset)
 	dev_dbg(nmk_chip->chip.dev, "%d: clearing interrupt mask\n", gpio);
 }
 
+static void nmk_prcm_altcx_set_mode(struct nmk_pinctrl *npct,
+	unsigned offset, unsigned alt_num)
+{
+	int i;
+	u16 reg;
+	u8 bit;
+	u8 alt_index;
+	const struct prcm_gpiocr_altcx_pin_desc *pin_desc;
+	const u16 *gpiocr_regs;
+
+	if (alt_num > PRCM_IDX_GPIOCR_ALTC_MAX) {
+		dev_err(npct->dev, "PRCM GPIOCR: alternate-C%i is invalid\n",
+			alt_num);
+		return;
+	}
+
+	for (i = 0 ; i < npct->soc->npins_altcx ; i++) {
+		if (npct->soc->altcx_pins[i].pin == offset)
+			break;
+	}
+	if (i == npct->soc->npins_altcx) {
+		dev_dbg(npct->dev, "PRCM GPIOCR: pin %i is not found\n",
+			offset);
+		return;
+	}
+
+	pin_desc = npct->soc->altcx_pins + i;
+	gpiocr_regs = npct->soc->prcm_gpiocr_registers;
+
+	/*
+	 * If alt_num is NULL, just clear current ALTCx selection
+	 * to make sure we come back to a pure ALTC selection
+	 */
+	if (!alt_num) {
+		for (i = 0 ; i < PRCM_IDX_GPIOCR_ALTC_MAX ; i++) {
+			if (pin_desc->altcx[i].used == true) {
+				reg = gpiocr_regs[pin_desc->altcx[i].reg_index];
+				bit = pin_desc->altcx[i].control_bit;
+				if (prcmu_read(reg) & BIT(bit)) {
+					prcmu_write_masked(reg, BIT(bit), 0);
+					dev_dbg(npct->dev,
+						"PRCM GPIOCR: pin %i: alternate-C%i has been disabled\n",
+						offset, i+1);
+				}
+			}
+		}
+		return;
+	}
+
+	alt_index = alt_num - 1;
+	if (pin_desc->altcx[alt_index].used == false) {
+		dev_warn(npct->dev,
+			"PRCM GPIOCR: pin %i: alternate-C%i does not exist\n",
+			offset, alt_num);
+		return;
+	}
+
+	/*
+	 * Check if any other ALTCx functions are activated on this pin
+	 * and disable it first.
+	 */
+	for (i = 0 ; i < PRCM_IDX_GPIOCR_ALTC_MAX ; i++) {
+		if (i == alt_index)
+			continue;
+		if (pin_desc->altcx[i].used == true) {
+			reg = gpiocr_regs[pin_desc->altcx[i].reg_index];
+			bit = pin_desc->altcx[i].control_bit;
+			if (prcmu_read(reg) & BIT(bit)) {
+				prcmu_write_masked(reg, BIT(bit), 0);
+				dev_dbg(npct->dev,
+					"PRCM GPIOCR: pin %i: alternate-C%i has been disabled\n",
+					offset, i+1);
+			}
+		}
+	}
+
+	reg = gpiocr_regs[pin_desc->altcx[alt_index].reg_index];
+	bit = pin_desc->altcx[alt_index].control_bit;
+	dev_dbg(npct->dev, "PRCM GPIOCR: pin %i: alternate-C%i has been selected\n",
+		offset, alt_index+1);
+	prcmu_write_masked(reg, BIT(bit), BIT(bit));
+}
+
 static void __nmk_config_pin(struct nmk_gpio_chip *nmk_chip, unsigned offset,
 			     pin_cfg_t cfg, bool sleep, unsigned int *slpmregs)
 {
@@ -1441,7 +1525,7 @@ static int nmk_pmx_enable(struct pinctrl_dev *pctldev, unsigned function,
 	 * IOFORCE will switch *all* ports to their sleepmode setting to as
 	 * to avoid glitches. (Not just one port!)
 	 */
-	glitch = (g->altsetting == NMK_GPIO_ALT_C);
+	glitch = ((g->altsetting & NMK_GPIO_ALT_C) == NMK_GPIO_ALT_C);
 
 	if (glitch) {
 		spin_lock_irqsave(&nmk_gpio_slpm_lock, flags);
@@ -1491,8 +1575,21 @@ static int nmk_pmx_enable(struct pinctrl_dev *pctldev, unsigned function,
 		 */
 		nmk_gpio_disable_lazy_irq(nmk_chip, bit);
 
-		__nmk_gpio_set_mode_safe(nmk_chip, bit, g->altsetting, glitch);
+		__nmk_gpio_set_mode_safe(nmk_chip, bit,
+			(g->altsetting & NMK_GPIO_ALT_C), glitch);
 		clk_disable(nmk_chip->clk);
+
+		/*
+		 * Call PRCM GPIOCR config function in case ALTC
+		 * has been selected:
+		 * - If selection is a ALTCx, some bits in PRCM GPIOCR registers
+		 *   must be set.
+		 * - If selection is pure ALTC and previous selection was ALTCx,
+		 *   then some bits in PRCM GPIOCR registers must be cleared.
+		 */
+		if ((g->altsetting & NMK_GPIO_ALT_C) == NMK_GPIO_ALT_C)
+			nmk_prcm_altcx_set_mode(npct, g->pins[i],
+				g->altsetting >> NMK_GPIO_ALT_CX_SHIFT);
 	}
 
 	/* When all pins are successfully reconfigured we get here */