path: root/drivers/tty/serial/stm32-usart.c

/*
 * Copyright (C) Maxime Coquelin 2015
 * Authors:  Maxime Coquelin <mcoquelin.stm32@gmail.com>
 *	     Gerald Baeza <gerald.baeza@st.com>
 * License terms:  GNU General Public License (GPL), version 2
 *
 * Inspired by st-asc.c from STMicroelectronics (c)
 */

#if defined(CONFIG_SERIAL_STM32_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/module.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/platform_device.h>
#include <linux/io.h>
#include <linux/irq.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/delay.h>
#include <linux/spinlock.h>
#include <linux/pm_runtime.h>
#include <linux/of.h>
#include <linux/of_platform.h>
#include <linux/serial_core.h>
#include <linux/clk.h>

#define DRIVER_NAME "stm32-usart"

struct stm32_usart_offsets {
	u8 cr1;
	u8 cr2;
	u8 cr3;
	u8 brr;
	u8 gtpr;
	u8 rtor;
	u8 rqr;
	u8 isr;
	u8 icr;
	u8 rdr;
	u8 tdr;
};

struct stm32_usart_config {
	u8 uart_enable_bit; /* USART_CR1_UE */
	bool has_7bits_data;
};

struct stm32_usart_info {
	struct stm32_usart_offsets ofs;
	struct stm32_usart_config cfg;
};

#define UNDEF_REG ~0

/* Register offsets */
struct stm32_usart_info stm32f4_info = {
	.ofs = {
		.isr	= 0x00,
		.rdr	= 0x04,
		.tdr	= 0x04,
		.brr	= 0x08,
		.cr1	= 0x0c,
		.cr2	= 0x10,
		.cr3	= 0x14,
		.gtpr	= 0x18,
		.rtor	= UNDEF_REG,
		.rqr	= UNDEF_REG,
		.icr	= UNDEF_REG,
	},
	.cfg = {
		.uart_enable_bit = 13,
		.has_7bits_data = false,
	}
};

struct stm32_usart_info stm32f7_info = {
	.ofs = {
		.cr1	= 0x00,
		.cr2	= 0x04,
		.cr3	= 0x08,
		.brr	= 0x0c,
		.gtpr	= 0x10,
		.rtor	= 0x14,
		.rqr	= 0x18,
		.isr	= 0x1c,
		.icr	= 0x20,
		.rdr	= 0x24,
		.tdr	= 0x28,
	},
	.cfg = {
		.uart_enable_bit = 0,
		.has_7bits_data = true,
	}
};

/* USART_SR (F4) / USART_ISR (F7) */
#define USART_SR_PE		BIT(0)
#define USART_SR_FE		BIT(1)
#define USART_SR_NF		BIT(2)
#define USART_SR_ORE		BIT(3)
#define USART_SR_IDLE		BIT(4)
#define USART_SR_RXNE		BIT(5)
#define USART_SR_TC		BIT(6)
#define USART_SR_TXE		BIT(7)
#define USART_SR_LBD		BIT(8)
#define USART_SR_CTSIF		BIT(9)
#define USART_SR_CTS		BIT(10)		/* F7 */
#define USART_SR_RTOF		BIT(11)		/* F7 */
#define USART_SR_EOBF		BIT(12)		/* F7 */
#define USART_SR_ABRE		BIT(14)		/* F7 */
#define USART_SR_ABRF		BIT(15)		/* F7 */
#define USART_SR_BUSY		BIT(16)		/* F7 */
#define USART_SR_CMF		BIT(17)		/* F7 */
#define USART_SR_SBKF		BIT(18)		/* F7 */
#define USART_SR_TEACK		BIT(21)		/* F7 */
#define USART_SR_ERR_MASK	(USART_SR_LBD | USART_SR_ORE | \
				 USART_SR_FE | USART_SR_PE)
/* Dummy bits */
#define USART_SR_DUMMY_RX	BIT(16)

/* USART_DR */
#define USART_DR_MASK		GENMASK(8, 0)

/* USART_BRR */
#define USART_BRR_DIV_F_MASK	GENMASK(3, 0)
#define USART_BRR_DIV_M_MASK	GENMASK(15, 4)
#define USART_BRR_DIV_M_SHIFT	4

/* USART_CR1 */
#define USART_CR1_SBK		BIT(0)
#define USART_CR1_RWU		BIT(1)		/* F4 */
#define USART_CR1_RE		BIT(2)
#define USART_CR1_TE		BIT(3)
#define USART_CR1_IDLEIE	BIT(4)
#define USART_CR1_RXNEIE	BIT(5)
#define USART_CR1_TCIE		BIT(6)
#define USART_CR1_TXEIE		BIT(7)
#define USART_CR1_PEIE		BIT(8)
#define USART_CR1_PS		BIT(9)
#define USART_CR1_PCE		BIT(10)
#define USART_CR1_WAKE		BIT(11)
#define USART_CR1_M		BIT(12)
#define USART_CR1_M0		BIT(12)		/* F7 */
#define USART_CR1_MME		BIT(13)		/* F7 */
#define USART_CR1_CMIE		BIT(14)		/* F7 */
#define USART_CR1_OVER8		BIT(15)
#define USART_CR1_DEDT_MASK	GENMASK(20, 16)	/* F7 */
#define USART_CR1_DEAT_MASK	GENMASK(25, 21)	/* F7 */
#define USART_CR1_RTOIE		BIT(26)		/* F7 */
#define USART_CR1_EOBIE		BIT(27)		/* F7 */
#define USART_CR1_M1		BIT(28)		/* F7 */
#define USART_CR1_IE_MASK	(GENMASK(8, 4) | BIT(14) | BIT(26) | BIT(27))

/* USART_CR2 */
#define USART_CR2_ADD_MASK	GENMASK(3, 0)	/* F4 */
#define USART_CR2_ADDM7		BIT(4)		/* F7 */
#define USART_CR2_LBDL		BIT(5)
#define USART_CR2_LBDIE		BIT(6)
#define USART_CR2_LBCL		BIT(8)
#define USART_CR2_CPHA		BIT(9)
#define USART_CR2_CPOL		BIT(10)
#define USART_CR2_CLKEN		BIT(11)
#define USART_CR2_STOP_2B	BIT(13)
#define USART_CR2_STOP_MASK	GENMASK(13, 12)
#define USART_CR2_LINEN		BIT(14)
#define USART_CR2_SWAP		BIT(15)		/* F7 */
#define USART_CR2_RXINV		BIT(16)		/* F7 */
#define USART_CR2_TXINV		BIT(17)		/* F7 */
#define USART_CR2_DATAINV	BIT(18)		/* F7 */
#define USART_CR2_MSBFIRST	BIT(19)		/* F7 */
#define USART_CR2_ABREN		BIT(20)		/* F7 */
#define USART_CR2_ABRMOD_MASK	GENMASK(22, 21)	/* F7 */
#define USART_CR2_RTOEN		BIT(23)		/* F7 */
#define USART_CR2_ADD_F7_MASK	GENMASK(31, 24)	/* F7 */

/* USART_CR3 */
#define USART_CR3_EIE		BIT(0)
#define USART_CR3_IREN		BIT(1)
#define USART_CR3_IRLP		BIT(2)
#define USART_CR3_HDSEL		BIT(3)
#define USART_CR3_NACK		BIT(4)
#define USART_CR3_SCEN		BIT(5)
#define USART_CR3_DMAR		BIT(6)
#define USART_CR3_DMAT		BIT(7)
#define USART_CR3_RTSE		BIT(8)
#define USART_CR3_CTSE		BIT(9)
#define USART_CR3_CTSIE		BIT(10)
#define USART_CR3_ONEBIT	BIT(11)
#define USART_CR3_OVRDIS	BIT(12)		/* F7 */
#define USART_CR3_DDRE		BIT(13)		/* F7 */
#define USART_CR3_DEM		BIT(14)		/* F7 */
#define USART_CR3_DEP		BIT(15)		/* F7 */
#define USART_CR3_SCARCNT_MASK	GENMASK(19, 17)	/* F7 */

/* USART_GTPR */
#define USART_GTPR_PSC_MASK	GENMASK(7, 0)
#define USART_GTPR_GT_MASK	GENMASK(15, 8)

/* USART_RTOR */
#define USART_RTOR_RTO_MASK	GENMASK(23, 0)	/* F7 */
#define USART_RTOR_BLEN_MASK	GENMASK(31, 24)	/* F7 */

/* USART_RQR */
#define USART_RQR_ABRRQ		BIT(0)		/* F7 */
#define USART_RQR_SBKRQ		BIT(1)		/* F7 */
#define USART_RQR_MMRQ		BIT(2)		/* F7 */
#define USART_RQR_RXFRQ		BIT(3)		/* F7 */
#define USART_RQR_TXFRQ		BIT(4)		/* F7 */

/* USART_ICR */
#define USART_ICR_PECF		BIT(0)		/* F7 */
#define USART_ICR_FFECF		BIT(1)		/* F7 */
#define USART_ICR_NCF		BIT(2)		/* F7 */
#define USART_ICR_ORECF		BIT(3)		/* F7 */
#define USART_ICR_IDLECF	BIT(4)		/* F7 */
#define USART_ICR_TCCF		BIT(6)		/* F7 */
#define USART_ICR_LBDCF		BIT(8)		/* F7 */
#define USART_ICR_CTSCF		BIT(9)		/* F7 */
#define USART_ICR_RTOCF		BIT(11)		/* F7 */
#define USART_ICR_EOBCF		BIT(12)		/* F7 */
#define USART_ICR_CMCF		BIT(17)		/* F7 */

#define STM32_SERIAL_NAME "ttyS"
#define STM32_MAX_PORTS 6

struct stm32_port {
	struct uart_port port;
	struct clk *clk;
	struct stm32_usart_info *info;
	bool hw_flow_control;
};

static struct stm32_port stm32_ports[STM32_MAX_PORTS];
static struct uart_driver stm32_usart_driver;

static void stm32_stop_tx(struct uart_port *port);

static inline struct stm32_port *to_stm32_port(struct uart_port *port)
{
	return container_of(port, struct stm32_port, port);
}

static void stm32_set_bits(struct uart_port *port, u32 reg, u32 bits)
{
	u32 val;

	val = readl_relaxed(port->membase + reg);
	val |= bits;
	writel_relaxed(val, port->membase + reg);
}

static void stm32_clr_bits(struct uart_port *port, u32 reg, u32 bits)
{
	u32 val;

	val = readl_relaxed(port->membase + reg);
	val &= ~bits;