/*
 * Copyright (c) 2023 TOKITA Hiroshi <tokita.hiroshi@fujitsu.com>
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#define DT_DRV_COMPAT renesas_ra_uart_sci

#include <zephyr/drivers/uart.h>
#include <zephyr/drivers/clock_control.h>
#include <zephyr/drivers/pinctrl.h>
#include <zephyr/spinlock.h>

#include <zephyr/logging/log.h>

LOG_MODULE_REGISTER(ra_uart_sci, CONFIG_UART_LOG_LEVEL);

struct uart_ra_cfg {
	mem_addr_t regs;
	const struct device *clock_dev;
	clock_control_subsys_t clock_id;
	const struct pinctrl_dev_config *pcfg;
};

struct uart_ra_data {
	struct uart_config current_config;
	uint32_t clk_rate;
	struct k_spinlock lock;
};

#define REG_MASK(reg) (BIT_MASK(_CONCAT(reg, _LEN)) << _CONCAT(reg, _POS))

/* Registers */
#define SMR  0x00 /*!< Serial Mode Register             */
#define BRR  0x01 /*!< Bit Rate Register                */
#define SCR  0x02 /*!< Serial Control Register          */
#define TDR  0x03 /*!< Transmit Data Register           */
#define SSR  0x04 /*!< Serial Status Register           */
#define RDR  0x05 /*!< Receive Data Register            */
#define SEMR 0x07 /*!< Serial Extended Mode Register    */
#define MDDR 0x12 /*!< Modulation Duty Register         */
#define LSR  0x18 /*!< Line Status Register             */

/*
 * SMR (Serial Mode Register)
 *
 * - CKS[0..2]:  Clock Select
 * - MP[2..3]:   Multi-Processor Mode(Valid only in asynchronous mode)
 * - STOP[3..4]: Stop Bit Length(Valid only in asynchronous mode)
 * - PM[4..5]:   Parity Mode (Valid only when the PE bit is 1)
 * - PE[5..6]:   Parity Enable(Valid only in asynchronous mode)
 * - CHR[6..7]:  Character Length(Valid only in asynchronous mode)
 * - CM[7..8]:   Communication Mode
 */
#define SMR_CKS_POS  (0)
#define SMR_CKS_LEN  (2)
#define SMR_MP_POS   (2)
#define SMR_MP_LEN   (1)
#define SMR_STOP_POS (3)
#define SMR_STOP_LEN (1)
#define SMR_PM_POS   (4)
#define SMR_PM_LEN   (1)
#define SMR_PE_POS   (5)
#define SMR_PE_LEN   (1)
#define SMR_CHR_POS  (6)
#define SMR_CHR_LEN  (1)
#define SMR_CM_POS   (7)
#define SMR_CM_LEN   (1)

/**
 * SCR (Serial Control Register)
 *
 * - CKE[0..2]:  Clock Enable
 * - TEIE[2..3]: Transmit End Interrupt Enable
 * - MPIE[3..4]: Multi-Processor Interrupt Enable (Valid in asynchronous
 * - RE[4..5]:   Receive Enable
 * - TE[5..6]:   Transmit Enable
 * - RIE[6..7]:  Receive Interrupt Enable
 * - TIE[7..8]:  Transmit Interrupt Enable
 */
#define SCR_CKE_POS  (0)
#define SCR_CKE_LEN  (2)
#define SCR_TEIE_POS (2)
#define SCR_TEIE_LEN (1)
#define SCR_MPIE_POS (3)
#define SCR_MPIE_LEN (1)
#define SCR_RE_POS   (4)
#define SCR_RE_LEN   (1)
#define SCR_TE_POS   (5)
#define SCR_TE_LEN   (1)
#define SCR_RIE_POS  (6)
#define SCR_RIE_LEN  (1)
#define SCR_TIE_POS  (7)
#define SCR_TIE_LEN  (1)

/**
 * SSR (Serial Status Register)
 *
 * - MPBT[0..1]: Multi-Processor Bit Transfer
 * - MPB[1..2]:  Multi-Processor
 * - TEND[2..3]: Transmit End Flag
 * - PER[3..4]:  Parity Error Flag
 * - FER[4..5]:  Framing Error Flag
 * - ORER[5..6]: Overrun Error Flag
 * - RDRF[6..7]: Receive Data Full Flag
 * - TDRE[7..8]: Transmit Data Empty Flag
 */
#define SSR_MPBT_POS (0)
#define SSR_MPBT_LEN (1)
#define SSR_MPB_POS  (1)
#define SSR_MPB_LEN  (1)
#define SSR_TEND_POS (2)
#define SSR_TEND_LEN (1)
#define SSR_PER_POS  (3)
#define SSR_PER_LEN  (1)
#define SSR_FER_POS  (4)
#define SSR_FER_LEN  (1)
#define SSR_ORER_POS (5)
#define SSR_ORER_LEN (1)
#define SSR_RDRF_POS (6)
#define SSR_RDRF_LEN (1)
#define SSR_TDRE_POS (7)
#define SSR_TDRE_LEN (1)

/**
 * SEMR (Serial Extended Mode Register)
 *
 * - ACS0[0..1]:    Asynchronous Mode Clock Source Select
 * - PADIS[1..2]:   Preamble function Disable
 * - BRME[2..3]:    Bit Rate Modulation Enable
 * - ABCSE[3..4]:   Asynchronous Mode Extended Base Clock Select
 * - ABCS[4..5]:    Asynchronous Mode Base Clock Select
 * - NFEN[5..6]:    Digital Noise Filter Function Enable
 * - BGDM[6..7]:    Baud Rate Generator Double-Speed Mode Select
 * - RXDESEL[7..8]: Asynchronous Start Bit Edge Detection Select
 */
#define SEMR_ACS0_POS    (0)
#define SEMR_ACS0_LEN    (1)
#define SEMR_PADIS_POS   (1)
#define SEMR_PADIS_LEN   (1)
#define SEMR_BRME_POS    (2)
#define SEMR_BRME_LEN    (1)
#define SEMR_ABCSE_POS   (3)
#define SEMR_ABCSE_LEN   (1)
#define SEMR_ABCS_POS    (4)
#define SEMR_ABCS_LEN    (1)
#define SEMR_NFEN_POS    (5)
#define SEMR_NFEN_LEN    (1)
#define SEMR_BGDM_POS    (6)
#define SEMR_BGDM_LEN    (1)
#define SEMR_RXDESEL_POS (7)
#define SEMR_RXDESEL_LEN (1)

/**
 * LSR (Line Status Register)
 *
 * - ORER[0..1]:  Overrun Error Flag
 * - FNUM[2..7]:  Framing Error Count
 * - PNUM[8..13]: Parity Error Count
 */
#define LSR_ORER_POS (0)
#define LSR_ORER_LEN (1)
#define LSR_FNUM_POS (2)
#define LSR_FNUM_LEN (5)
#define LSR_PNUM_POS (8)
#define LSR_PNUM_LEN (5)

static uint8_t uart_ra_read_8(const struct device *dev,
			   uint32_t offs)
{
	const struct uart_ra_cfg *config = dev->config;

	return sys_read8(config->regs + offs);
}

static void uart_ra_write_8(const struct device *dev,
			    uint32_t offs, uint8_t value)
{
	const struct uart_ra_cfg *config = dev->config;

	sys_write8(value, config->regs + offs);
}

static uint16_t uart_ra_read_16(const struct device *dev,
				uint32_t offs)
{
	const struct uart_ra_cfg *config = dev->config;

	return sys_read16(config->regs + offs);
}

static void uart_ra_write_16(const struct device *dev,
			     uint32_t offs, uint16_t value)
{
	const struct uart_ra_cfg *config = dev->config;

	sys_write16(value, config->regs + offs);
}

static void uart_ra_set_baudrate(const struct device *dev,
				 uint32_t baud_rate)
{
	struct uart_ra_data *data = dev->data;
	uint8_t reg_val;

	reg_val = uart_ra_read_8(dev, SEMR);
	reg_val |= REG_MASK(SEMR_BGDM);
	reg_val &= ~(REG_MASK(SEMR_BRME) | REG_MASK(SEMR_ABCSE) | REG_MASK(SEMR_ABCS));
	uart_ra_write_8(dev, SEMR, reg_val);

	reg_val = (data->clk_rate / (16 * data->current_config.baudrate)) - 1;
	uart_ra_write_8(dev, BRR, reg_val);
}

static int uart_ra_poll_in(const struct device *dev, unsigned char *p_char)
{
	struct uart_ra_data *data = dev->data;
	int ret = 0;

	k_spinlock_key_t key = k_spin_lock(&data->lock);

	if ((uart_ra_read_8(dev, SSR) & REG_MASK(SSR_RDRF)) == 0) {
		ret = -1;
		goto unlock;
	}

	*p_char = uart_ra_read_8(dev, RDR);
unlock:
	k_spin_unlock(&data->lock, key);

	return ret;
}

static void uart_ra_poll_out(const struct device *dev, unsigned char out_char)
{
	struct uart_ra_data *data = dev->data;
	k_spinlock_key_t key = k_spin_lock(&data->lock);

	uart_ra_write_8(dev, TDR, out_char);
	while (!(uart_ra_read_8(dev, SSR) & REG_MASK(SSR_TEND)) ||
	       !(uart_ra_read_8(dev, SSR) & REG_MASK(SSR_TDRE))) {
		;
	}
	k_spin_unlock(&data->lock, key);
}

static int uart_ra_configure(const struct device *dev,
			     const struct uart_config *cfg)
{
	struct uart_ra_data *data = dev->data;

	uint16_t reg_val;
	k_spinlock_key_t key;

	if (cfg->parity != UART_CFG_PARITY_NONE || cfg->stop_bits != UART_CFG_STOP_BITS_1 ||
	    cfg->data_bits != UART_CFG_DATA_BITS_8 || cfg->flow_ctrl != UART_CFG_FLOW_CTRL_NONE) {
		return -ENOTSUP;
	}

	key = k_spin_lock(&data->lock);

	/* Disable Transmit and Receive */
	reg_val = uart_ra_read_8(dev, SCR);
	reg_val &= ~(REG_MASK(SCR_TE) | REG_MASK(SCR_RE));
	uart_ra_write_8(dev, SCR, reg_val);

	/* Resetting Errors Registers */
	reg_val = uart_ra_read_8(dev, SSR);
	reg_val &= ~(REG_MASK(SSR_PER) | REG_MASK(SSR_FER) | REG_MASK(SSR_ORER) |
		     REG_MASK(SSR_RDRF) | REG_MASK(SSR_TDRE));
	uart_ra_write_8(dev, SSR, reg_val);

	reg_val = uart_ra_read_16(dev, LSR);
	reg_val &= ~(REG_MASK(LSR_ORER));
	uart_ra_write_16(dev, LSR, reg_val);

	/* Select internal clock */
	reg_val = uart_ra_read_8(dev, SCR);
	reg_val &= ~(REG_MASK(SCR_CKE));
	uart_ra_write_8(dev, SCR, reg_val);

	/* Serial Configuration (8N1) & Clock divider selection */
	reg_val = uart_ra_read_8(dev, SMR);
	reg_val &= ~(REG_MASK(SMR_CM) | REG_MASK(SMR_CHR) | REG_MASK(SMR_PE) | REG_MASK(SMR_PM) |
		     REG_MASK(SMR_STOP) | REG_MASK(SMR_CKS));
	uart_ra_write_8(dev, SMR, reg_val);

	/* Set baudrate */
	uart_ra_set_baudrate(dev, cfg->baudrate);

	/* Enable Transmit & Receive + disable Interrupts */
	reg_val = uart_ra_read_8(dev, SCR);
	reg_val |= (REG_MASK(SCR_TE) | REG_MASK(SCR_RE));
	reg_val &=
		~(REG_MASK(SCR_TIE) | REG_MASK(SCR_RIE) | REG_MASK(SCR_MPIE) | REG_MASK(SCR_TEIE));
	uart_ra_write_8(dev, SCR, reg_val);

	data->current_config = *cfg;

	k_spin_unlock(&data->lock, key);

	return 0;
}

#ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE
static int uart_ra_config_get(const struct device *dev,
			      struct uart_config *cfg)
{
	struct uart_ra_data *data = dev->data;

	*cfg = data->current_config;

	return 0;
}
#endif /* CONFIG_UART_USE_RUNTIME_CONFIGURE */

static int uart_ra_init(const struct device *dev)
{
	const struct uart_ra_cfg *config = dev->config;
	struct uart_ra_data *data = dev->data;
	int ret;

	/* Configure dt provided device signals when available */
	ret = pinctrl_apply_state(config->pcfg, PINCTRL_STATE_DEFAULT);
	if (ret < 0) {
		return ret;
	}

	if (!device_is_ready(config->clock_dev)) {
		return -ENODEV;
	}

	ret = clock_control_on(config->clock_dev, config->clock_id);
	if (ret < 0) {
		return ret;
	}

	ret = clock_control_get_rate(config->clock_dev, config->clock_id, &data->clk_rate);
	if (ret < 0) {
		return ret;
	}

	DEVICE_MMIO_MAP(dev, K_MEM_CACHE_NONE);

	ret = uart_ra_configure(dev, &data->current_config);
	if (ret != 0) {
		return ret;
	}

	return 0;
}

static const struct uart_driver_api uart_ra_driver_api = {
	.poll_in = uart_ra_poll_in,
	.poll_out = uart_ra_poll_out,
#ifdef CONFIG_UART_USE_RUNTIME_CONFIGURE
	.configure = uart_ra_configure,
	.config_get = uart_ra_config_get,
#endif
};

/* Device Instantiation */
#define UART_RCAR_INIT_CFG(n)                                                                      \
	PINCTRL_DT_DEFINE(DT_INST_PARENT(n));                                                      \
	static const struct uart_ra_cfg uart_ra_cfg_##n = {                                        \
		.regs = DT_REG_ADDR(DT_INST_PARENT(n)),                                            \
		.clock_dev = DEVICE_DT_GET(DT_CLOCKS_CTLR(DT_INST_PARENT(n))),                     \
		.clock_id =                                                                        \
			(clock_control_subsys_t)DT_CLOCKS_CELL_BY_IDX(DT_INST_PARENT(n), 0, id),   \
		.pcfg = PINCTRL_DT_DEV_CONFIG_GET(DT_INST_PARENT(n)),                              \
	}

#define UART_RCAR_INIT(n)							\
	UART_RCAR_INIT_CFG(n);                                                  \
										\
	static struct uart_ra_data uart_ra_data_##n = {				\
		.current_config = {						\
			.baudrate = DT_INST_PROP(n, current_speed),		\
			.parity = UART_CFG_PARITY_NONE,				\
			.stop_bits = UART_CFG_STOP_BITS_1,			\
			.data_bits = UART_CFG_DATA_BITS_8,			\
			.flow_ctrl = UART_CFG_FLOW_CTRL_NONE,			\
		},								\
	};									\
										\
	DEVICE_DT_INST_DEFINE(n,						\
			      uart_ra_init,					\
			      NULL,						\
			      &uart_ra_data_##n,				\
			      &uart_ra_cfg_##n,					\
			      PRE_KERNEL_1, CONFIG_SERIAL_INIT_PRIORITY,	\
			      &uart_ra_driver_api);				\
										\

DT_INST_FOREACH_STATUS_OKAY(UART_RCAR_INIT)