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>

arch/arm/plat-nomadik/include/plat/gpio-nomadik.h

@@ -45,6 +45,12 @@
 #define NMK_GPIO_ALT_B	2
 #define NMK_GPIO_ALT_C	(NMK_GPIO_ALT_A | NMK_GPIO_ALT_B)
 
+#define NMK_GPIO_ALT_CX_SHIFT 2
+#define NMK_GPIO_ALT_C1	((1<<NMK_GPIO_ALT_CX_SHIFT) | NMK_GPIO_ALT_C)
+#define NMK_GPIO_ALT_C2	((2<<NMK_GPIO_ALT_CX_SHIFT) | NMK_GPIO_ALT_C)
+#define NMK_GPIO_ALT_C3	((3<<NMK_GPIO_ALT_CX_SHIFT) | NMK_GPIO_ALT_C)
+#define NMK_GPIO_ALT_C4	((4<<NMK_GPIO_ALT_CX_SHIFT) | NMK_GPIO_ALT_C)
+
 /* Pull up/down values */
 enum nmk_gpio_pull {
 	NMK_GPIO_PULL_NONE,

arch/arm/plat-nomadik/include/plat/pincfg.h

@@ -25,6 +25,8 @@
  *	bit 19..20 - SLPM direction
  *	bit 21..22 - SLPM Value (if output)
  *	bit 23..25 - PDIS value (if input)
+ *	bit	26 - Gpio mode
+ *	bit	27 - Sleep mode
  *
  * to facilitate the definition, the following macros are provided
  *

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 */

drivers/pinctrl/pinctrl-nomadik.h

@@ -8,6 +8,78 @@
 #define PINCTRL_NMK_DB8500	1
 #define PINCTRL_NMK_DB8540	2
 
+#define PRCM_GPIOCR_ALTCX(pin_num,\
+	altc1_used, altc1_ri, altc1_cb,\
+	altc2_used, altc2_ri, altc2_cb,\
+	altc3_used, altc3_ri, altc3_cb,\
+	altc4_used, altc4_ri, altc4_cb)\
+{\
+	.pin = pin_num,\
+	.altcx[PRCM_IDX_GPIOCR_ALTC1] = {\
+		.used = altc1_used,\
+		.reg_index = altc1_ri,\
+		.control_bit = altc1_cb\
+	},\
+	.altcx[PRCM_IDX_GPIOCR_ALTC2] = {\
+		.used = altc2_used,\
+		.reg_index = altc2_ri,\
+		.control_bit = altc2_cb\
+	},\
+	.altcx[PRCM_IDX_GPIOCR_ALTC3] = {\
+		.used = altc3_used,\
+		.reg_index = altc3_ri,\
+		.control_bit = altc3_cb\
+	},\
+	.altcx[PRCM_IDX_GPIOCR_ALTC4] = {\
+		.used = altc4_used,\
+		.reg_index = altc4_ri,\
+		.control_bit = altc4_cb\
+	},\
+}
+
+/**
+ * enum prcm_gpiocr_reg_index
+ * Used to reference an PRCM GPIOCR register address.
+ */
+enum prcm_gpiocr_reg_index {
+	PRCM_IDX_GPIOCR1,
+	PRCM_IDX_GPIOCR2,
+	PRCM_IDX_GPIOCR3
+};
+/**
+ * enum prcm_gpiocr_altcx_index
+ * Used to reference an Other alternate-C function.
+ */
+enum prcm_gpiocr_altcx_index {
+	PRCM_IDX_GPIOCR_ALTC1,
+	PRCM_IDX_GPIOCR_ALTC2,
+	PRCM_IDX_GPIOCR_ALTC3,
+	PRCM_IDX_GPIOCR_ALTC4,
+	PRCM_IDX_GPIOCR_ALTC_MAX,
+};
+
+/**
+ * struct prcm_gpio_altcx - Other alternate-C function
+ * @used: other alternate-C function availability
+ * @reg_index: PRCM GPIOCR register index used to control the function
+ * @control_bit: PRCM GPIOCR bit used to control the function
+ */
+struct prcm_gpiocr_altcx {
+	bool used:1;
+	u8 reg_index:2;
+	u8 control_bit:5;
+} __packed;
+
+/**
+ * struct prcm_gpio_altcx_pin_desc - Other alternate-C pin
+ * @pin: The pin number
+ * @altcx: array of other alternate-C[1-4] functions
+ */
+struct prcm_gpiocr_altcx_pin_desc {
+	unsigned short pin;
+	struct prcm_gpiocr_altcx altcx[PRCM_IDX_GPIOCR_ALTC_MAX];
+};
+
 /**
  * struct nmk_function - Nomadik pinctrl mux function
  * @name: The name of the function, exported to pinctrl core.
@@ -50,6 +122,9 @@ struct nmk_pingroup {
  * @nfunction:	The number of entries in @functions.
  * @groups:	An array describing all pin groups the pin SoC supports.
  * @ngroups:	The number of entries in @groups.
+ * @altcx_pins:	The pins that support Other alternate-C function on this SoC
+ * @npins_altcx: The number of Other alternate-C pins
+ * @prcm_gpiocr_registers: The array of PRCM GPIOCR registers on this SoC
  */
 struct nmk_pinctrl_soc_data {
 	struct pinctrl_gpio_range *gpio_ranges;
@@ -60,6 +135,9 @@ struct nmk_pinctrl_soc_data {
 	unsigned nfunctions;
 	const struct nmk_pingroup *groups;
 	unsigned ngroups;
+	const struct prcm_gpiocr_altcx_pin_desc *altcx_pins;
+	unsigned npins_altcx;
+	const u16 *prcm_gpiocr_registers;
 };
 
 #ifdef CONFIG_PINCTRL_STN8815