/*
 * Copyright (c) 2018 Linaro Limited
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <kernel.h>
#include <arch/cpu.h>
#include <init.h>
#include <device.h>
#include <soc.h>
#include <drivers/uart.h>


/*
 * UART PL011 register map structure
 */
struct pl011_regs {
	u32_t dr;			/* data register */
	union {
		u32_t rsr;
		u32_t ecr;
	};
	u32_t reserved_0[4];
	u32_t fr;			/* flags register */
	u32_t reserved_1;
	u32_t ilpr;
	u32_t ibrd;
	u32_t fbrd;
	u32_t lcr_h;
	u32_t cr;
	u32_t ifls;
	u32_t imsc;
	u32_t ris;
	u32_t mis;
	u32_t icr;
	u32_t dmacr;
};

/* Device data structure */
struct pl011_data {
	u32_t baud_rate;	/* Baud rate */
#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	uart_irq_callback_user_data_t irq_cb;
	void *irq_cb_data;
#endif
};

#define PL011_BIT_MASK(x, y) (((2 << x) - 1) << y)

/* PL011 Uart Flags Register */
#define PL011_FR_CTS		BIT(0)	/* clear to send - inverted */
#define PL011_FR_DSR		BIT(1)	/* data set ready - inverted */
#define PL011_FR_DCD		BIT(2)	/* data carrier detect - inverted */
#define PL011_FR_BUSY		BIT(3)	/* busy transmitting data */
#define PL011_FR_RXFE		BIT(4)	/* receive FIFO empty */
#define PL011_FR_TXFF		BIT(5)	/* transmit FIFO full */
#define PL011_FR_RXFF		BIT(6)	/* receive FIFO full */
#define PL011_FR_TXFE		BIT(7)	/* transmit FIFO empty */
#define PL011_FR_RI		BIT(8)	/* ring indicator - inverted */

/* PL011 Integer baud rate register */
#define PL011_IBRD_BAUD_DIVINT_MASK	0xff	/* 16 bits of divider */

/* PL011 Fractional baud rate register */
#define PL011_FBRD_BAUD_DIVFRAC		0x3f
#define PL011_FBRD_WIDTH		6u

/* PL011 Receive status register / error clear register */
#define PL011_RSR_ECR_FE	BIT(0)	/* framing error */
#define PL011_RSR_ECR_PE	BIT(1)	/* parity erorr */
#define PL011_RSR_ECR_BE	BIT(2)	/* break error */
#define PL011_RSR_ECR_OE	BIT(3)	/* overrun error */

#define PL011_RSR_ERROR_MASK	(PL011_RSR_ECR_FE | PL011_RSR_ECR_PE | \
		PL011_RSR_ECR_BE | PL011_RSR_ECR_OE)

/* PL011 Line Control Register  */
#define PL011_LCRH_BRK		BIT(0)	/* send break */
#define PL011_LCRH_PEN		BIT(1)	/* enable parity */
#define PL011_LCRH_EPS		BIT(2)	/* select even parity */
#define PL011_LCRH_STP2		BIT(3)	/* select two stop bits */
#define PL011_LCRH_FEN		BIT(4)	/* enable FIFOs */
#define PL011_LCRH_WLEN_SHIFT	5	/* word length */
#define PL011_LCRH_WLEN_WIDTH	2
#define PL011_LCRH_SPS		BIT(7)	/* stick parity bit */

#define PL011_LCRH_WLEN_SIZE(x) (x - 5)

#define PL011_LCRH_FORMAT_MASK	(PL011_LCRH_PEN | PL011_LCRH_EPS | \
		PL011_LCRH_SPS | \
		PL011_BIT_MASK(PL011_LCRH_WLEN_WIDTH, PL011_LCRH_WLEN_SHIFT))

#define PL011_LCRH_PARTIY_EVEN	(PL011_LCRH_PEN | PL011_LCRH_EPS)
#define PL011_LCRH_PARITY_ODD	(PL011_LCRH_PEN)
#define PL011_LCRH_PARITY_NONE	(0)

/* PL011 Control Register */
#define PL011_CR_UARTEN		BIT(0)	/* enable uart operations */
#define PL011_CR_SIREN		BIT(1)	/* enable  IrDA SIR */
#define PL011_CR_SIRLP		BIT(2)	/* IrDA SIR low power mode */
#define PL011_CR_LBE		BIT(7)	/* loop back enable */
#define PL011_CR_TXE		BIT(8)	/* transmit enable */
#define PL011_CR_RXE		BIT(9)	/* receive enable */
#define PL011_CR_DTR		BIT(10)	/* data transmit ready */
#define PL011_CR_RTS		BIT(11)	/* request to send */
#define PL011_CR_Out1		BIT(12)
#define PL011_CR_Out2		BIT(13)
#define PL011_CR_RTSEn		BIT(14)	/* RTS hw flow control enable */
#define PL011_CR_CTSEn		BIT(15)	/* CTS hw flow control enable */

/* PL011 Interrupt Fifo Level Select Register */
#define PL011_IFLS_TXIFLSEL_SHIFT	0	/* bits 2:0 */
#define PL011_IFLS_TXIFLSEL_WIDTH	3
#define PL011_IFLS_RXIFLSEL_SHIFT	3	/* bits 5:3 */
#define PL011_IFLS_RXIFLSEL_WIDTH	3

/* PL011 Interrupt Mask Set/Clear Register */
#define PL011_IMSC_RIMIM	BIT(0)	/* RTR modem interrupt mask */
#define PL011_IMSC_CTSMIM	BIT(1)	/* CTS modem interrupt mask */
#define PL011_IMSC_DCDMIM	BIT(2)	/* DCD modem interrupt mask */
#define PL011_IMSC_DSRMIM	BIT(3)	/* DSR modem interrupt mask */
#define PL011_IMSC_RXIM		BIT(4)	/* receive interrupt mask */
#define PL011_IMSC_TXIM		BIT(5)	/* transmit interrupt mask */
#define PL011_IMSC_RTIM		BIT(6)	/* receive timeout interrupt mask */
#define PL011_IMSC_FEIM		BIT(7)	/* framine error interrupt mask */
#define PL011_IMSC_PEIM		BIT(8)	/* parity error interrupt mask */
#define PL011_IMSC_BEIM		BIT(9)	/* break error interrupt mask */
#define PL011_IMSC_OEIM		BIT(10)	/* overrun error interrutpt mask */

#define PL011_IMSC_ERROR_MASK	(PL011_IMSC_FEIM | \
		PL011_IMSC_PEIM | PL011_IMSC_BEIM | \
		PL011_IMSC_OEIM)

#define PL011_IMSC_MASK_ALL (PL011_IMSC_OEIM | PL011_IMSC_BEIM | \
		PL011_IMSC_PEIM | PL011_IMSC_FEIM | \
		PL011_IMSC_RIMIM | PL011_IMSC_CTSMIM | \
		PL011_IMSC_DCDMIM | PL011_IMSC_DSRMIM | \
		PL011_IMSC_RXIM | PL011_IMSC_TXIM | \
		PL011_IMSC_RTIM)

#define DEV_CFG(dev) \
	((const struct uart_device_config * const)(dev)->config->config_info)
#define DEV_DATA(dev) \
	((struct pl011_data *)(dev)->driver_data)
#define PL011_REGS(dev) \
	((volatile struct pl011_regs  *)(DEV_CFG(dev))->base)

static void pl011_enable(struct device *dev)
{
	PL011_REGS(dev)->cr |=  PL011_CR_UARTEN;
}

static void pl011_disable(struct device *dev)
{
	PL011_REGS(dev)->cr &= ~PL011_CR_UARTEN;
}

static void pl011_enable_fifo(struct device *dev)
{
	PL011_REGS(dev)->lcr_h |= PL011_LCRH_FEN;
}

static void pl011_disable_fifo(struct device *dev)
{
	PL011_REGS(dev)->lcr_h &= ~PL011_LCRH_FEN;
}

static int pl011_set_baudrate(struct device *dev,
			      u32_t clk, u32_t baudrate)
{
	/* Avoiding float calculations, bauddiv is left shifted by 6 */
	u64_t bauddiv = (((u64_t)clk) << PL011_FBRD_WIDTH)
				/ (baudrate * 16U);

	/* Valid bauddiv value
	 * uart_clk (min) >= 16 x baud_rate (max)
	 * uart_clk (max) <= 16 x 65535 x baud_rate (min)
	 */
	if ((bauddiv < (1u << PL011_FBRD_WIDTH))
		|| (bauddiv > (65535u << PL011_FBRD_WIDTH))) {
		return -EINVAL;
	}

	PL011_REGS(dev)->ibrd = bauddiv >> PL011_FBRD_WIDTH;
	PL011_REGS(dev)->fbrd = bauddiv & ((1u << PL011_FBRD_WIDTH) - 1u);

	__DMB();

	/* In order to internally update the contents of ibrd or fbrd, a
	 * lcr_h write must always be performed at the end
	 * ARM DDI 0183F, Pg 3-13
	 */
	PL011_REGS(dev)->lcr_h = PL011_REGS(dev)->lcr_h;

	return 0;
}

static bool pl011_is_readable(struct device *dev)
{
	if ((PL011_REGS(dev)->cr & PL011_CR_UARTEN) &&
	    (PL011_REGS(dev)->cr & PL011_CR_RXE) &&
	   ((PL011_REGS(dev)->fr & PL011_FR_RXFE) == 0U)) {
		return true;
	}

	return false;
}

static int pl011_poll_in(struct device *dev, unsigned char *c)
{
	if (!pl011_is_readable(dev)) {
		return -1;
	}

	/* got a character */
	*c = (unsigned char)PL011_REGS(dev)->dr;

	return PL011_REGS(dev)->rsr & PL011_RSR_ERROR_MASK;
}

static void pl011_poll_out(struct device *dev,
					     unsigned char c)
{
	/* Wait for space in FIFO */
	while (PL011_REGS(dev)->fr & PL011_FR_TXFF) {
		; /* Wait */
	}

	/* Send a character */
	PL011_REGS(dev)->dr = (u32_t)c;
}

#ifdef CONFIG_UART_INTERRUPT_DRIVEN
static int pl011_fifo_fill(struct device *dev,
				    const u8_t *tx_data, int len)
{
	u8_t num_tx = 0U;

	while (!(PL011_REGS(dev)->fr & PL011_FR_TXFF) &&
	       (len - num_tx > 0)) {
		PL011_REGS(dev)->dr = tx_data[num_tx++];
	}
	return num_tx;
}

static int pl011_fifo_read(struct device *dev,
				    u8_t *rx_data, const int len)
{
	u8_t num_rx = 0U;

	while ((len - num_rx > 0) &&
	       !(PL011_REGS(dev)->fr & PL011_FR_RXFE)) {
		rx_data[num_rx++] = PL011_REGS(dev)->dr;
	}

	return num_rx;
}

static void pl011_irq_tx_enable(struct device *dev)
{
	PL011_REGS(dev)->imsc |= PL011_IMSC_TXIM;
}

static void pl011_irq_tx_disable(struct device *dev)
{
	PL011_REGS(dev)->imsc &= ~PL011_IMSC_TXIM;
}

static int pl011_irq_tx_complete(struct device *dev)
{
	/* check for TX FIFO empty */
	return PL011_REGS(dev)->fr & PL011_FR_TXFE;
}

static int pl011_irq_tx_ready(struct device *dev)
{
	return ((PL011_REGS(dev)->cr & PL011_CR_TXE) &&
		(PL011_REGS(dev)->imsc & PL011_IMSC_TXIM) &&
		pl011_irq_tx_complete(dev));
}

static void pl011_irq_rx_enable(struct device *dev)
{
	PL011_REGS(dev)->imsc |= PL011_IMSC_RXIM |
				 PL011_IMSC_RTIM;
}

static void pl011_irq_rx_disable(struct device *dev)
{
	PL011_REGS(dev)->imsc &= ~(PL011_IMSC_RXIM |
				   PL011_IMSC_RTIM);
}

static int pl011_irq_rx_ready(struct device *dev)
{
	return ((PL011_REGS(dev)->cr & PL011_CR_RXE) &&
		(PL011_REGS(dev)->imsc & PL011_IMSC_RXIM) &&
		(!(PL011_REGS(dev)->fr & PL011_FR_RXFE)));
}

static void pl011_irq_err_enable(struct device *dev)
{
	/* enable framing, parity, break, and overrun */
	PL011_REGS(dev)->imsc |= PL011_IMSC_ERROR_MASK;
}

static void pl011_irq_err_disable(struct device *dev)
{
	PL011_REGS(dev)->imsc &= ~PL011_IMSC_ERROR_MASK;
}

static int pl011_irq_is_pending(struct device *dev)
{
	return pl011_irq_rx_ready(dev) || pl011_irq_tx_ready(dev);
}

static int pl011_irq_update(struct device *dev)
{
	return 1;
}

static void pl011_irq_callback_set(struct device *dev,
					    uart_irq_callback_user_data_t cb,
					    void *cb_data)
{
	DEV_DATA(dev)->irq_cb = cb;
	DEV_DATA(dev)->irq_cb_data = cb_data;
}
#endif /* CONFIG_UART_INTERRUPT_DRIVEN */

static const struct uart_driver_api pl011_driver_api = {
	.poll_in = pl011_poll_in,
	.poll_out = pl011_poll_out,
#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	.fifo_fill = pl011_fifo_fill,
	.fifo_read = pl011_fifo_read,
	.irq_tx_enable = pl011_irq_tx_enable,
	.irq_tx_disable = pl011_irq_tx_disable,
	.irq_tx_ready = pl011_irq_tx_ready,
	.irq_rx_enable = pl011_irq_rx_enable,
	.irq_rx_disable = pl011_irq_rx_disable,
	.irq_tx_complete = pl011_irq_tx_complete,
	.irq_rx_ready = pl011_irq_rx_ready,
	.irq_err_enable = pl011_irq_err_enable,
	.irq_err_disable = pl011_irq_err_disable,
	.irq_is_pending = pl011_irq_is_pending,
	.irq_update = pl011_irq_update,
	.irq_callback_set = pl011_irq_callback_set,
#endif /* CONFIG_UART_INTERRUPT_DRIVEN */
};

static int pl011_init(struct device *dev)
{
	int ret;
	u32_t lcrh;

	/* disable the uart */
	pl011_disable(dev);
	pl011_disable_fifo(dev);

	/* Set baud rate */
	ret = pl011_set_baudrate(dev, DEV_CFG(dev)->sys_clk_freq,
				      DEV_DATA(dev)->baud_rate);
	if (ret != 0) {
		return ret;
	}

	/* Setting the default character format */
	lcrh = PL011_REGS(dev)->lcr_h & ~(PL011_LCRH_FORMAT_MASK);
	lcrh &= ~(BIT(0) | BIT(7));
	lcrh |= PL011_LCRH_WLEN_SIZE(8) << PL011_LCRH_WLEN_SHIFT;
	PL011_REGS(dev)->lcr_h = lcrh;

	/* Enabling the FIFOs */
	pl011_enable_fifo(dev);

	/* initialize all IRQs as masked */
	PL011_REGS(dev)->imsc = 0U;
	PL011_REGS(dev)->icr = PL011_IMSC_MASK_ALL;

	PL011_REGS(dev)->dmacr = 0U;
	__ISB();
	PL011_REGS(dev)->cr &= ~(BIT(14) | BIT(15) | BIT(1));
	PL011_REGS(dev)->cr |= PL011_CR_RXE | PL011_CR_TXE;
	__ISB();

#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	DEV_CFG(dev)->irq_config_func(dev);
#endif
	pl011_enable(dev);

	return 0;
}

#ifdef CONFIG_UART_INTERRUPT_DRIVEN
void pl011_isr(void *arg)
{
	struct device *dev = arg;
	struct pl011_data *data = DEV_DATA(dev);

	/* Verify if the callback has been registered */
	if (data->irq_cb) {
		data->irq_cb(data->irq_cb_data);
	}
}
#endif /* CONFIG_UART_INTERRUPT_DRIVEN */


#ifdef CONFIG_UART_PL011_PORT0

#ifdef CONFIG_UART_INTERRUPT_DRIVEN
static void pl011_irq_config_func_0(struct device *dev);
#endif

static struct uart_device_config pl011_cfg_port_0 = {
	.base = (u8_t *)DT_PL011_PORT0_BASE_ADDRESS,
	.sys_clk_freq = DT_PL011_PORT0_CLOCK_FREQUENCY,
#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	.irq_config_func = pl011_irq_config_func_0,
#endif
};

static struct pl011_data pl011_data_port_0 = {
	.baud_rate = DT_PL011_PORT0_BAUD_RATE,
};

DEVICE_AND_API_INIT(pl011_port_0,
		    DT_PL011_PORT0_NAME,
		    &pl011_init,
		    &pl011_data_port_0,
		    &pl011_cfg_port_0, PRE_KERNEL_1,
		    CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
		    &pl011_driver_api);

#ifdef CONFIG_UART_INTERRUPT_DRIVEN
static void pl011_irq_config_func_0(struct device *dev)
{
	IRQ_CONNECT(DT_PL011_PORT0_IRQ_TX,
		    DT_PL011_PORT0_IRQ_PRI,
		    pl011_isr,
		    DEVICE_GET(pl011_port_0),
		    0);
	irq_enable(DT_PL011_PORT0_IRQ_TX);

	IRQ_CONNECT(DT_PL011_PORT0_IRQ_RX,
		    DT_PL011_PORT0_IRQ_PRI,
		    pl011_isr,
		    DEVICE_GET(pl011_port_0),
		    0);
	irq_enable(DT_PL011_PORT0_IRQ_RX);

	IRQ_CONNECT(DT_PL011_PORT0_IRQ_RXTIM,
		    DT_PL011_PORT0_IRQ_PRI,
		    pl011_isr,
		    DEVICE_GET(pl011_port_0),
		    0);
	irq_enable(DT_PL011_PORT0_IRQ_RXTIM);
}
#endif

#endif /* CONFIG_UART_PL011_PORT0 */

#ifdef CONFIG_UART_PL011_PORT1

#ifdef CONFIG_UART_INTERRUPT_DRIVEN
static void pl011_irq_config_func_1(struct device *dev);
#endif

static struct uart_device_config pl011_cfg_port_1 = {
	.base = (u8_t *)DT_PL011_PORT1_BASE_ADDRESS,
	.sys_clk_freq = DT_PL011_PORT1_CLOCK_FREQUENCY,
#ifdef CONFIG_UART_INTERRUPT_DRIVEN
	.irq_config_func = pl011_irq_config_func_1,
#endif
};

static struct pl011_data pl011_data_port_1 = {
	.baud_rate = DT_PL011_PORT1_BAUD_RATE,
};

DEVICE_AND_API_INIT(pl011_port_1,
		    DT_PL011_PORT1_NAME,
		    &pl011_init,
		    &pl011_data_port_1,
		    &pl011_cfg_port_1, PRE_KERNEL_1,
		    CONFIG_KERNEL_INIT_PRIORITY_DEVICE,
		    &pl011_driver_api);

#ifdef CONFIG_UART_INTERRUPT_DRIVEN
static void pl011_irq_config_func_1(struct device *dev)
{
	IRQ_CONNECT(DT_PL011_PORT1_IRQ_TX,
		    DT_PL011_PORT1_IRQ_PRI,
		    pl011_isr,
		    DEVICE_GET(pl011_port_1),
		    0);
	irq_enable(DT_PL011_PORT1_IRQ_TX);

	IRQ_CONNECT(DT_PL011_PORT1_IRQ_RX,
		    DT_PL011_PORT1_IRQ_PRI,
		    pl011_isr,
		    DEVICE_GET(pl011_port_1),
		    0);
	irq_enable(DT_PL011_PORT1_IRQ_RX);

	IRQ_CONNECT(DT_PL011_PORT1_IRQ_RXTIM,
		    DT_PL011_PORT1_IRQ_PRI,
		    pl011_isr,
		    DEVICE_GET(pl011_port_1),
		    0);
	irq_enable(DT_PL011_PORT1_IRQ_RXTIM);
}
#endif

#endif /* CONFIG_UART_PL011_PORT1 */