path: root/drivers/tty/serial/sprd_serial.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2012-2015 Spreadtrum Communications Inc.
 */

#if defined(CONFIG_SERIAL_SPRD_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/clk.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/dma/sprd-dma.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/platform_device.h>
#include <linux/serial_core.h>
#include <linux/serial.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>

/* device name */
#define UART_NR_MAX		8
#define SPRD_TTY_NAME		"ttyS"
#define SPRD_FIFO_SIZE		128
#define SPRD_DEF_RATE		26000000
#define SPRD_BAUD_IO_LIMIT	3000000
#define SPRD_TIMEOUT		256000

/* the offset of serial registers and BITs for them */
/* data registers */
#define SPRD_TXD		0x0000
#define SPRD_RXD		0x0004

/* line status register and its BITs  */
#define SPRD_LSR		0x0008
#define SPRD_LSR_OE		BIT(4)
#define SPRD_LSR_FE		BIT(3)
#define SPRD_LSR_PE		BIT(2)
#define SPRD_LSR_BI		BIT(7)
#define SPRD_LSR_TX_OVER	BIT(15)

/* data number in TX and RX fifo */
#define SPRD_STS1		0x000C
#define SPRD_RX_FIFO_CNT_MASK	GENMASK(7, 0)
#define SPRD_TX_FIFO_CNT_MASK	GENMASK(15, 8)

/* interrupt enable register and its BITs */
#define SPRD_IEN		0x0010
#define SPRD_IEN_RX_FULL	BIT(0)
#define SPRD_IEN_TX_EMPTY	BIT(1)
#define SPRD_IEN_BREAK_DETECT	BIT(7)
#define SPRD_IEN_TIMEOUT	BIT(13)

/* interrupt clear register */
#define SPRD_ICLR		0x0014
#define SPRD_ICLR_TIMEOUT	BIT(13)

/* line control register */
#define SPRD_LCR		0x0018
#define SPRD_LCR_STOP_1BIT	0x10
#define SPRD_LCR_STOP_2BIT	0x30
#define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
#define SPRD_LCR_DATA_LEN5	0x0
#define SPRD_LCR_DATA_LEN6	0x4
#define SPRD_LCR_DATA_LEN7	0x8
#define SPRD_LCR_DATA_LEN8	0xc
#define SPRD_LCR_PARITY		(BIT(0) | BIT(1))
#define SPRD_LCR_PARITY_EN	0x2
#define SPRD_LCR_EVEN_PAR	0x0
#define SPRD_LCR_ODD_PAR	0x1

/* control register 1 */
#define SPRD_CTL1		0x001C
#define SPRD_DMA_EN		BIT(15)
#define RX_HW_FLOW_CTL_THLD	BIT(6)
#define RX_HW_FLOW_CTL_EN	BIT(7)
#define TX_HW_FLOW_CTL_EN	BIT(8)
#define RX_TOUT_THLD_DEF	0x3E00
#define RX_HFC_THLD_DEF		0x40

/* fifo threshold register */
#define SPRD_CTL2		0x0020
#define THLD_TX_EMPTY		0x40
#define THLD_TX_EMPTY_SHIFT	8
#define THLD_RX_FULL		0x40
#define THLD_RX_FULL_MASK	GENMASK(6, 0)

/* config baud rate register */
#define SPRD_CLKD0		0x0024
#define SPRD_CLKD0_MASK		GENMASK(15, 0)
#define SPRD_CLKD1		0x0028
#define SPRD_CLKD1_MASK		GENMASK(20, 16)
#define SPRD_CLKD1_SHIFT	16

/* interrupt mask status register */
#define SPRD_IMSR		0x002C
#define SPRD_IMSR_RX_FIFO_FULL	BIT(0)
#define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
#define SPRD_IMSR_BREAK_DETECT	BIT(7)
#define SPRD_IMSR_TIMEOUT	BIT(13)
#define SPRD_DEFAULT_SOURCE_CLK	26000000

#define SPRD_RX_DMA_STEP	1
#define SPRD_RX_FIFO_FULL	1
#define SPRD_TX_FIFO_FULL	0x20
#define SPRD_UART_RX_SIZE	(UART_XMIT_SIZE / 4)

struct sprd_uart_dma {
	struct dma_chan *chn;
	unsigned char *virt;
	dma_addr_t phys_addr;
	dma_cookie_t cookie;
	u32 trans_len;
	bool enable;
};

struct sprd_uart_port {
	struct uart_port port;
	char name[16];
	struct clk *clk;
	struct sprd_uart_dma tx_dma;
	struct sprd_uart_dma rx_dma;
	dma_addr_t pos;
	unsigned char *rx_buf_tail;
};

static struct sprd_uart_port *sprd_port[UART_NR_MAX];
static int sprd_ports_num;

static int sprd_start_dma_rx(struct uart_port *port);
static int sprd_tx_dma_config(struct uart_port *port);

static inline unsigned int serial_in(struct uart_port *port,
				     unsigned int offset)
{
	return readl_relaxed(port->membase + offset);
}

static inline void serial_out(struct uart_port *port, unsigned int offset,
			      int value)
{
	writel_relaxed(value, port->membase + offset);
}

static unsigned int sprd_tx_empty(struct uart_port *port)
{
	if (serial_in(port, SPRD_STS1) & SPRD_TX_FIFO_CNT_MASK)
		return 0;
	else
		return TIOCSER_TEMT;
}

static unsigned int sprd_get_mctrl(struct uart_port *port)
{
	return TIOCM_DSR | TIOCM_CTS;
}

static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
	/* nothing to do */
}

static void sprd_stop_rx(struct uart_port *port)
{
	struct sprd_uart_port *sp =
		container_of(port, struct sprd_uart_port, port);
	unsigned int ien, iclr;

	if (sp-&g