drivers/pinctrl/pfc_rcar.c

/*
 * Copyright (c) 2021 IoT.bzh
 *
 * SPDX-License-Identifier: Apache-2.0
 *
 */

#define DT_DRV_COMPAT renesas_rcar_pfc

#include <zephyr/devicetree.h>
#include <zephyr/drivers/pinctrl.h>
#include <soc.h>
#include <zephyr/sys/util.h>

#define PFC_REG_BASE  DT_INST_REG_ADDR(0)
#define PFC_RCAR_PMMR 0x0
#define PFC_RCAR_GPSR 0x100
#define PFC_RCAR_IPSR 0x200

/*
 * Each drive step is either encoded in 2 or 3 bits.
 * So based on a 24 mA maximum value each step is either
 * 24/4 mA or 24/8 mA.
 */
#define PFC_RCAR_DRIVE_MAX 24U
#define PFC_RCAR_DRIVE_STEP(size) \
	(size == 2 ? PFC_RCAR_DRIVE_MAX / 4 : PFC_RCAR_DRIVE_MAX / 8)

/* Some registers such as IPSR GPSR or DRVCTRL are protected and
 * must be preceded to a write to PMMR with the inverse value.
 */
static void pfc_rcar_write(uint32_t offs, uint32_t val)
{
	sys_write32(~val, PFC_REG_BASE + PFC_RCAR_PMMR);
	sys_write32(val, PFC_REG_BASE + offs);
}

/* Set the pin either in gpio or peripheral */
static void pfc_rcar_set_gpsr(uint16_t pin, bool peripheral)
{
	uint8_t bank = pin / 32;
	uint8_t bit = pin % 32;
	uint32_t val = sys_read32(PFC_REG_BASE + PFC_RCAR_GPSR +
				  bank * sizeof(uint32_t));

	if (peripheral) {
		val |= BIT(bit);
	} else {
		val &= ~BIT(bit);
	}
	pfc_rcar_write(PFC_RCAR_GPSR + bank * sizeof(uint32_t), val);
}

/* Set peripheral function */
static void pfc_rcar_set_ipsr(const struct rcar_pin_func *rcar_func)
{
	uint16_t reg_offs = PFC_RCAR_IPSR + rcar_func->bank * sizeof(uint32_t);
	uint32_t val = sys_read32(PFC_REG_BASE + reg_offs);

	val &= ~(0xFU << rcar_func->shift);
	val |= (rcar_func->func << rcar_func->shift);
	pfc_rcar_write(reg_offs, val);
}

static uint32_t pfc_rcar_get_drive_reg(uint16_t pin, uint8_t *offset,
				       uint8_t *size)
{
	const struct pfc_drive_reg *drive_regs = pfc_rcar_get_drive_regs();

	while (drive_regs->reg != 0U) {
		for (size_t i = 0U; i < ARRAY_SIZE(drive_regs->fields); i++) {
			if (drive_regs->fields[i].pin == pin) {
				*offset = drive_regs->fields[i].offset;
				*size = drive_regs->fields[i].size;
				return drive_regs->reg;
			}
		}
		drive_regs++;
	}

	return 0;
}

/*
 * Maximum drive strength is 24mA. This value can be lowered
 * using DRVCTRLx registers, some pins have 8 steps (3 bits size encoded)
 * some have 4 steps (2 bits size encoded).
 */
static int pfc_rcar_set_drive_strength(uint16_t pin, uint8_t strength)
{
	uint8_t offset, size, step;
	uint32_t reg, val;

	reg = pfc_rcar_get_drive_reg(pin, &offset, &size);
	if (reg == 0U) {
		return -EINVAL;
	}

	step = PFC_RCAR_DRIVE_STEP(size);
	if ((strength < step) || (strength > PFC_RCAR_DRIVE_MAX)) {
		return -EINVAL;
	}

	/* Convert the value from mA based on a full drive strength
	 * value of 24mA.
	 */
	strength = (strength / step) - 1U;
	/* clear previous drive strength value */
	val = sys_read32(PFC_REG_BASE + reg);
	val &= ~GENMASK(offset + size - 1U, offset);
	val |= strength << offset;

	pfc_rcar_write(reg, val);

	return 0;
}

static const struct pfc_bias_reg *pfc_rcar_get_bias_reg(uint16_t pin,
							uint8_t *bit)
{
	const struct pfc_bias_reg *bias_regs = pfc_rcar_get_bias_regs();

	/* Loop around all the registers to find the bit for a given pin */
	while (bias_regs->puen && bias_regs->pud) {
		for (size_t i = 0U; i < ARRAY_SIZE(bias_regs->pins); i++) {
			if (bias_regs->pins[i] == pin) {
				*bit = i;
				return bias_regs;
			}
		}
		bias_regs++;
	}

	return NULL;
}

int pfc_rcar_set_bias(uint16_t pin, uint16_t flags)
{
	uint32_t val;
	uint8_t bit;
	const struct pfc_bias_reg *bias_reg = pfc_rcar_get_bias_reg(pin, &bit);

	if (bias_reg == NULL) {
		return -EINVAL;
	}

	/* pull enable/disable*/
	val = sys_read32(PFC_REG_BASE + bias_reg->puen);
	if ((flags & RCAR_PIN_FLAGS_PUEN) == 0U) {
		sys_write32(val & ~BIT(bit), PFC_REG_BASE + bias_reg->puen);
		return 0;
	}
	sys_write32(val | BIT(bit), PFC_REG_BASE + bias_reg->puen);

	/* pull - up/down */
	val = sys_read32(PFC_REG_BASE + bias_reg->pud);
	if (flags & RCAR_PIN_FLAGS_PUD) {
		sys_write32(val | BIT(bit), PFC_REG_BASE + bias_reg->pud);
	} else {
		sys_write32(val & ~BIT(bit), PFC_REG_BASE + bias_reg->pud);
	}
	return 0;
}

int pinctrl_configure_pin(const pinctrl_soc_pin_t *pin)
{
	int ret = 0;

	/* Set pin as GPIO if capable */
	if (RCAR_IS_GP_PIN(pin->pin)) {
		pfc_rcar_set_gpsr(pin->pin, false);
	} else if ((pin->flags & RCAR_PIN_FLAGS_FUNC_SET) == 0U) {
		/* A function must be set for non GPIO capable pin */
		return -EINVAL;
	}

	/* Select function for pin */
	if ((pin->flags & RCAR_PIN_FLAGS_FUNC_SET) != 0U) {
		pfc_rcar_set_ipsr(&pin->func);

		if (RCAR_IS_GP_PIN(pin->pin)) {
			pfc_rcar_set_gpsr(pin->pin, true);
		}

		if ((pin->flags & RCAR_PIN_FLAGS_PULL_SET) != 0U) {
			ret = pfc_rcar_set_bias(pin->pin, pin->flags);
			if (ret < 0) {
				return ret;
			}
		}
	}

	if (pin->drive_strength != 0U) {
		ret = pfc_rcar_set_drive_strength(pin->pin,
						  pin->drive_strength);
	}

	return ret;
}

int pinctrl_configure_pins(const pinctrl_soc_pin_t *pins, uint8_t pin_cnt,
			   uintptr_t reg)
{
	int ret = 0;

	ARG_UNUSED(reg);
	while (pin_cnt-- > 0U) {
		ret = pinctrl_configure_pin(pins++);
		if (ret < 0) {
			break;
		}
	}

	return ret;
}