Message-Id: <1404491651-1388-4-git-send-email-bigeasy@linutronix.de>
Date:	Fri,  4 Jul 2014 18:34:11 +0200
From:	Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:	linux-serial@...r.kernel.org
Cc:	linux-kernel@...r.kernel.org, balbi@...com,
	linux-omap@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
	tony@...mide.com, Sebastian Andrzej Siewior <bigeasy@...utronix.de>
Subject: [RFC PATCH 4/4] tty: serial: Add 8250-core based omap driver v2

This patch provides a 8250-core based UART driver for the internal OMAP
UART. The longterm goal is to provide the same functionality as the
current OMAP uart driver and hopefully DMA support which could borrowed
from the 8250-core.

It has been only tested as console UART.
The tty name is ttyS based instead of ttyO.

Missing:
- throttle callback
- custom startup + shutdown callback for wakeup-irq handling.
- RS485 handling.

v1…v2:
	- added runtime PM. Could somebody could plese double check
	  this? I seems to be enabled and nothing explodes. However
	  serial_omap_get_context_loss_count() & enable_wakeup() are
	  NULL pointer (in the omap-serial driver). So I am not sure how
	  this supposed to work :)
	- added omap_8250_set_termios()

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
---
 drivers/tty/serial/8250/8250_core.c |   8 +
 drivers/tty/serial/8250/8250_omap.c | 840 ++++++++++++++++++++++++++++++++++++
 drivers/tty/serial/8250/Kconfig     |   9 +
 drivers/tty/serial/8250/Makefile    |   1 +
 include/uapi/linux/serial_core.h    |   3 +-
 5 files changed, 860 insertions(+), 1 deletion(-)
 create mode 100644 drivers/tty/serial/8250/8250_omap.c

diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index b0b9abb..3f2f533 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -261,6 +261,12 @@ static const struct serial8250_config uart_config[] = {
 		.fcr		= UART_FCR_ENABLE_FIFO | UART_FCR_R_TRIG_10,
 		.flags		= UART_CAP_FIFO | UART_CAP_AFE,
 	},
+	[PORT_OMAP_16750] = {
+		.name		= "OMAP",
+		.fifo_size	= 64,
+		.tx_loadsz	= 64,
+		.flags		= UART_CAP_FIFO | UART_CAP_EFR | UART_CAP_SLEEP,
+	},
 	[PORT_TEGRA] = {
 		.name		= "Tegra",
 		.fifo_size	= 32,
@@ -1347,6 +1353,8 @@ static void serial8250_stop_rx(struct uart_port *port)
 	pm_runtime_get_sync(port->dev);
 
 	up->ier &= ~UART_IER_RLSI;
+	if (port->type == PORT_OMAP_16750)
+		up->ier &= ~UART_IER_RDI;
 	up->port.read_status_mask &= ~UART_LSR_DR;
 	serial_port_out(port, UART_IER, up->ier);
 
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
new file mode 100644
index 0000000..63f91fc
--- /dev/null
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -0,0 +1,840 @@
+/*
+ * 8250-core based driver for the OMAP internal UART
+ *
+ *  Copyright (C) 2014 Sebastian Andrzej Siewior
+ *
+ */
+
+#include <linux/device.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/serial_8250.h>
+#include <linux/serial_core.h>
+#include <linux/serial_reg.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/of.h>
+#include <linux/delay.h>
+#include <linux/pm_runtime.h>
+#include <linux/console.h>
+#include <linux/pm_qos.h>
+
+#include "8250.h"
+
+#define UART_DLL_EM 9
+#define UART_DLM_EM 10
+
+#define DEFAULT_CLK_SPEED	48000000 /* 48 Mhz*/
+
+#define UART_ERRATA_i202_MDR1_ACCESS	(1 << 0)
+#define OMAP_UART_WER_HAS_TX_WAKEUP	(1 << 1)
+
+/* SCR register bitmasks */
+#define OMAP_UART_SCR_RX_TRIG_GRANU1_MASK	(1 << 7)
+#define OMAP_UART_SCR_TX_TRIG_GRANU1_MASK	(1 << 6)
+#define OMAP_UART_SCR_TX_EMPTY			(1 << 3)
+
+/* MVR register bitmasks */
+#define OMAP_UART_MVR_SCHEME_SHIFT	30
+#define OMAP_UART_LEGACY_MVR_MAJ_MASK	0xf0
+#define OMAP_UART_LEGACY_MVR_MAJ_SHIFT	4
+#define OMAP_UART_LEGACY_MVR_MIN_MASK	0x0f
+#define OMAP_UART_MVR_MAJ_MASK		0x700
+#define OMAP_UART_MVR_MAJ_SHIFT		8
+#define OMAP_UART_MVR_MIN_MASK		0x3f
+
+/* Enable XON/XOFF flow control on output */
+#define OMAP_UART_SW_TX		0x08
+/* Enable XON/XOFF flow control on input */
+#define OMAP_UART_SW_RX		0x02
+#define OMAP_UART_SW_CLR	0xF0
+#define OMAP_UART_TCR_TRIG	0x0F
+
+#define UART_BUILD_REVISION(x, y)	(((x) << 8) | (y))
+
+#define OMAP_UART_REV_46 0x0406
+#define OMAP_UART_REV_52 0x0502
+#define OMAP_UART_REV_63 0x0603
+
+struct serial8250_omap_priv {
+	int line;
+	u32 habit;
+	u32 fcr;
+	u32 mdr1;
+	u32 efr;
+	u32 quot;
+	u32 scr;
+	bool is_suspending;
+	int wakeirq;
+	int wakeups_enabled;
+	int context_loss_cnt;
+	u32 latency;
+	u32 calc_latency;
+	struct pm_qos_request pm_qos_request;
+	struct work_struct qos_work;
+};
+
+static u32 uart_read(struct uart_8250_port *up, u32 reg)
+{
+	return readl(up->port.membase + (reg << up->port.regshift));
+}
+
+static void uart_write(struct uart_8250_port *up, u32 reg, u32 val)
+{
+	writel(val, up->port.membase + (reg << up->port.regshift));
+}
+
+/*
+ * Work Around for Errata i202 (2430, 3430, 3630, 4430 and 4460)
+ * The access to uart register after MDR1 Access
+ * causes UART to corrupt data.
+ *
+ * Need a delay =
+ * 5 L4 clock cycles + 5 UART functional clock cycle (@48MHz = ~0.2uS)
+ * give 10 times as much
+ */
+static void omap_8250_mdr1_errataset(struct uart_8250_port *up, u8 mdr1)
+{
+	struct serial8250_omap_priv *priv = up->port.private_data;
+	u8 timeout = 255;
+
+	serial_out(up, UART_OMAP_MDR1, mdr1);
+	udelay(2);
+	serial_out(up, UART_FCR, priv->fcr | UART_FCR_CLEAR_XMIT |
+			UART_FCR_CLEAR_RCVR);
+	/*
+	 * Wait for FIFO to empty: when empty, RX_FIFO_E bit is 0 and
+	 * TX_FIFO_E bit is 1.
+	 */
+	while (UART_LSR_THRE != (serial_in(up, UART_LSR) &
+				(UART_LSR_THRE | UART_LSR_DR))) {
+		timeout--;
+		if (!timeout) {
+			/* Should *never* happen. we warn and carry on */
+			dev_crit(up->port.dev, "Errata i202: timedout %x\n",
+						serial_in(up, UART_LSR));
+			break;
+		}
+		udelay(1);
+	}
+}
+
+static void omap_8250_get_divisor(struct uart_port *port, unsigned int baud,
+		struct serial8250_omap_priv *priv)
+{
+	unsigned int uartclk = port->uartclk;
+	unsigned int div_13, div_16;
+	unsigned int abs_d13, abs_d16;
+
+	/*
+	 * Old custom speed handling.
+	 */
+	if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST) {
+		priv->quot = port->custom_divisor & 0xffff;
+		/*
+		 * I assume that nobody is using this. But hey, if somebody
+		 * would like to specify the divisor _and_ the mode then the
+		 * driver is ready and waiting for it.
+		 */
+		if (port->custom_divisor & (1 << 16))
+			priv->mdr1 = UART_OMAP_MDR1_13X_MODE;
+		else
+			priv->mdr1 = UART_OMAP_MDR1_16X_MODE;
+		return;
+	}
+	div_13 = DIV_ROUND_CLOSEST(uartclk, 13 * baud);
+	div_16 = DIV_ROUND_CLOSEST(uartclk, 16 * baud);
+
+	abs_d13 = abs(baud - port->uartclk / 13 / div_13);
+	abs_d16 = abs(baud - port->uartclk / 16 / div_16);
+
+	if (abs_d13 >= abs_d16) {
+		priv->mdr1 = UART_OMAP_MDR1_16X_MODE;
+		priv->quot = div_16;
+	} else {
+		priv->mdr1 = UART_OMAP_MDR1_13X_MODE;
+		priv->quot = div_13;
+	}
+}
+
+/*
+ * OMAP can use "CLK / (16 or 13) / div" for baud rate. And then we have have
+ * some differences in how we want to handle flow control.
+ */
+static void omap_8250_set_termios(struct uart_port *port,
+		struct ktermios *termios, struct ktermios *old)
+{
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+	struct serial8250_omap_priv *priv = up->port.private_data;
+	unsigned char cval = 0;
+	unsigned long flags = 0;
+	unsigned int baud;
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+		cval = UART_LCR_WLEN5;
+		break;
+	case CS6:
+		cval = UART_LCR_WLEN6;
+		break;
+	case CS7:
+		cval = UART_LCR_WLEN7;
+		break;
+	default:
+	case CS8:
+		cval = UART_LCR_WLEN8;
+		break;
+	}
+
+	if (termios->c_cflag & CSTOPB)
+		cval |= UART_LCR_STOP;
+	if (termios->c_cflag & PARENB)
+		cval |= UART_LCR_PARITY;
+	if (!(termios->c_cflag & PARODD))
+		cval |= UART_LCR_EPAR;
+	if (termios->c_cflag & CMSPAR)
+		cval |= UART_LCR_SPAR;
+
+	/*
+	 * Ask the core to calculate the divisor for us.
+	 */
+	baud = uart_get_baud_rate(port, termios, old,
+			port->uartclk / 16 / 0xffff,
+			port->uartclk / 13);
+	omap_8250_get_divisor(port, baud, priv);
+
+	/*
+	 * Ok, we're now changing the port state. Do it with
+	 * interrupts disabled.
+	 */
+	pm_runtime_get_sync(port->dev);
+	spin_lock_irqsave(&port->lock, flags);
+
+	/*
+	 * Update the per-port timeout.
+	 */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	up->port.read_status_mask = UART_LSR_OE | UART_LSR_THRE | UART_LSR_DR;
+	if (termios->c_iflag & INPCK)
+		up->port.read_status_mask |= UART_LSR_FE | UART_LSR_PE;
+	if (termios->c_iflag & (BRKINT | PARMRK))
+		up->port.read_status_mask |= UART_LSR_BI;
+
+	/*
+	 * Characters to ignore
+	 */
+	up->port.ignore_status_mask = 0;
+	if (termios->c_iflag & IGNPAR)
+		up->port.ignore_status_mask |= UART_LSR_PE | UART_LSR_FE;
+	if (termios->c_iflag & IGNBRK) {
+		up->port.ignore_status_mask |= UART_LSR_BI;
+		/*
+		 * If we're ignoring parity and break indicators,
+		 * ignore overruns too (for real raw support).
+		 */
+		if (termios->c_iflag & IGNPAR)
+			up->port.ignore_status_mask |= UART_LSR_OE;
+	}
+
+	/*
+	 * ignore all characters if CREAD is not set
+	 */
+	if ((termios->c_cflag & CREAD) == 0)
+		up->port.ignore_status_mask |= UART_LSR_DR;
+
+	/*
+	 * Modem status interrupts
+	 */
+	up->ier &= ~UART_IER_MSI;
+	if (UART_ENABLE_MS(&up->port, termios->c_cflag))
+		up->ier |= UART_IER_MSI;
+	serial_out(up, UART_IER, up->ier);
+
+	serial_out(up, UART_LCR, cval);         /* reset DLAB */
+	up->lcr = cval;
+
+	/* Up to here it was mostly serial8250_do_set_termios() */
+
+	/* FCR can be changed only when the
+	 * baud clock is not running
+	 * DLL_REG and DLH_REG set to 0.
+	 */
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+	serial_out(up, UART_DLL, 0);
+	serial_out(up, UART_DLM, 0);
+	serial_out(up, UART_LCR, 0);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, UART_EFR_ECB);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+	serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
+
+	priv->scr = OMAP_UART_SCR_RX_TRIG_GRANU1_MASK | OMAP_UART_SCR_TX_EMPTY;
+	/*
+	 * NOTE: Setting OMAP_UART_SCR_RX_TRIG_GRANU1_MASK sets Enables the
+	 * granularity of 1 for TRIGGER RX level. Along with setting RX FIFO
+	 * trigger level to 1 (as noted below, 16 characters) and TLR[3:0] to
+	 * zero this will result RX FIFO threshold level to 1 character.
+	 * Transmit FIFO threshold is set to 32 spaces. With SCR_TX_EMPTY set,
+	 * we receive an interrupt once TX FIFO (and shift) is empty as this is
+	 * what The irq routine currently expects to happen.
+	 */
+	priv->fcr = UART_FCR6_R_TRIGGER_16 | UART_FCR6_T_TRIGGER_24 |
+		UART_FCR_ENABLE_FIFO;
+
+	serial_out(up, UART_FCR, priv->fcr);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+	serial_out(up, UART_OMAP_SCR, priv->scr);
+
+	/* Reset UART_MCR_TCRTLR: this must be done with the EFR_ECB bit set */
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+	serial_out(up, UART_MCR, up->mcr);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, 0);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+
+	/* Protocol, Baud Rate, and Interrupt Settings */
+
+	if (priv->habit & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_8250_mdr1_errataset(up, UART_OMAP_MDR1_DISABLE);
+	else
+		serial_out(up, UART_OMAP_MDR1, UART_OMAP_MDR1_DISABLE);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, UART_EFR_ECB);
+
+	serial_out(up, UART_LCR, 0);
+	serial_out(up, UART_IER, 0);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+	serial_dl_write(up, priv->quot);
+
+	serial_out(up, UART_LCR, 0);
+	serial_out(up, UART_IER, up->ier);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+	serial_out(up, UART_EFR, 0);
+	serial_out(up, UART_LCR, up->lcr);
+
+	if (priv->habit & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_8250_mdr1_errataset(up, priv->mdr1);
+	else
+		serial_out(up, UART_OMAP_MDR1, priv->mdr1);
+
+	/* Configure flow control */
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+
+	/* XON1/XOFF1 accessible mode B, TCRTLR=0, ECB=0 */
+	serial_out(up, UART_XON1, termios->c_cc[VSTART]);
+	serial_out(up, UART_XOFF1, termios->c_cc[VSTOP]);
+
+	/* Enable access to TCR/TLR */
+	serial_out(up, UART_EFR, UART_EFR_ECB);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+	serial_out(up, UART_MCR, up->mcr | UART_MCR_TCRTLR);
+
+	serial_out(up, UART_TI752_TCR, OMAP_UART_TCR_TRIG);
+
+	priv->efr = 0;
+	if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW) {
+		/* Enable AUTORTS and AUTOCTS */
+		priv->efr |= UART_EFR_CTS | UART_EFR_RTS;
+
+		/* Ensure MCR RTS is asserted */
+		up->mcr |= UART_MCR_RTS;
+	}
+
+	if (up->port.flags & UPF_SOFT_FLOW) {
+		/*
+		 * IXON Flag:
+		 * Enable XON/XOFF flow control on input.
+		 * Receiver compares XON1, XOFF1.
+		 */
+		if (termios->c_iflag & IXON)
+			priv->efr |= OMAP_UART_SW_RX;
+
+		/*
+		 * IXOFF Flag:
+		 * Enable XON/XOFF flow control on output.
+		 * Transmit XON1, XOFF1
+		 */
+		if (termios->c_iflag & IXOFF)
+			priv->efr |= OMAP_UART_SW_TX;
+
+		/*
+		 * IXANY Flag:
+		 * Enable any character to restart output.
+		 * Operation resumes after receiving any
+		 * character after recognition of the XOFF character
+		 */
+		if (termios->c_iflag & IXANY)
+			up->mcr |= UART_MCR_XONANY;
+		else
+			up->mcr &= ~UART_MCR_XONANY;
+	}
+	serial_out(up, UART_MCR, up->mcr);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, 0);
+	serial_out(up, UART_LCR, up->lcr);
+
+	port->ops->set_mctrl(port, port->mctrl);
+
+	spin_unlock_irqrestore(&up->port.lock, flags);
+	pm_runtime_mark_last_busy(port->dev);
+	pm_runtime_put_autosuspend(port->dev);
+
+	/* calculate wakeup latency constraint */
+	priv->calc_latency = (USEC_PER_SEC * up->port.fifosize) / (baud / 8);
+	priv->latency = priv->calc_latency;
+	schedule_work(&priv->qos_work);
+
+	/* Don't rewrite B0 */
+	if (tty_termios_baud_rate(termios))
+		tty_termios_encode_baud_rate(termios, baud, baud);
+}
+
+/* same as 8250 except that we may have extra flow bits set in EFR */
+static void omap_8250_pm(struct uart_port *port, unsigned int state,
+		unsigned int oldstate)
+{
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+	struct serial8250_omap_priv *priv = up->port.private_data;
+
+	pm_runtime_get_sync(port->dev);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, priv->efr | UART_EFR_ECB);
+	serial_out(up, UART_LCR, 0);
+
+	serial_out(up, UART_IER, (state != 0) ? UART_IERX_SLEEP : 0);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+	serial_out(up, UART_EFR, priv->efr);
+	serial_out(up, UART_LCR, 0);
+
+	if (!device_may_wakeup(port->dev)) {
+		if (!state)
+			pm_runtime_forbid(port->dev);
+		else
+			pm_runtime_allow(port->dev);
+	}
+
+	pm_runtime_mark_last_busy(port->dev);
+	pm_runtime_put_autosuspend(port->dev);
+}
+
+static void omap_serial_fill_features_erratas(struct uart_8250_port *up,
+		struct serial8250_omap_priv *priv)
+{
+	u32 mvr, scheme;
+	u16 revision, major, minor;
+
+	mvr = uart_read(up, UART_OMAP_MVER);
+
+	/* Check revision register scheme */
+	scheme = mvr >> OMAP_UART_MVR_SCHEME_SHIFT;
+
+	switch (scheme) {
+	case 0: /* Legacy Scheme: OMAP2/3 */
+		/* MINOR_REV[0:4], MAJOR_REV[4:7] */
+		major = (mvr & OMAP_UART_LEGACY_MVR_MAJ_MASK) >>
+			OMAP_UART_LEGACY_MVR_MAJ_SHIFT;
+		minor = (mvr & OMAP_UART_LEGACY_MVR_MIN_MASK);
+		break;
+	case 1:
+		/* New Scheme: OMAP4+ */
+		/* MINOR_REV[0:5], MAJOR_REV[8:10] */
+		major = (mvr & OMAP_UART_MVR_MAJ_MASK) >>
+			OMAP_UART_MVR_MAJ_SHIFT;
+		minor = (mvr & OMAP_UART_MVR_MIN_MASK);
+		break;
+	default:
+		dev_warn(up->port.dev,
+				"Unknown revision, defaulting to highest\n");
+		/* highest possible revision */
+		major = 0xff;
+		minor = 0xff;
+	}
+	/* normalize revision for the driver */
+	revision = UART_BUILD_REVISION(major, minor);
+
+	switch (revision) {
+	case OMAP_UART_REV_46:
+		priv->habit = UART_ERRATA_i202_MDR1_ACCESS;
+		break;
+	case OMAP_UART_REV_52:
+		priv->habit = UART_ERRATA_i202_MDR1_ACCESS |
+				OMAP_UART_WER_HAS_TX_WAKEUP;
+		break;
+	case OMAP_UART_REV_63:
+		priv->habit = UART_ERRATA_i202_MDR1_ACCESS |
+			OMAP_UART_WER_HAS_TX_WAKEUP;
+		break;
+	default:
+		break;
+	}
+}
+
+static void serial_omap_uart_qos_work(struct work_struct *work)
+{
+	struct serial8250_omap_priv *priv;
+
+	priv = container_of(work, struct serial8250_omap_priv, qos_work);
+	pm_qos_update_request(&priv->pm_qos_request, priv->latency);
+}
+
+#if 0
+static int omap_8250_startup(struct uart_port *port)
+{
+	struct uart_8250_port *up =
+		container_of(port, struct uart_8250_port, port);
+	struct serial8250_omap_priv *priv = port->private_data;
+
+	int ret;
+
+	if (priv->wakeirq) {
+		ret = request_irq(priv->wakeirq, port->handle_irq,
+				port->irqflags, "wakeup irq", port);
+		if (ret)
+			return ret;
+		disable_irq(up->wakeirq);
+	}
+
+	ret = serial8250_do_startup(port);
+	if (ret)
+		goto out;
+
+	/* Enable module level wake up */
+	priv->wer = OMAP_UART_WER_MOD_WKUP;
+	if (priv->features & OMAP_UART_WER_HAS_TX_WAKEUP)
+		priv->wer |= OMAP_UART_TX_WAKEUP_EN;
+out:
+	if (priv->wakeirq)
+		free(priv->wakeirq, port);
+	return ret;
+}
+#endif
+
+static int serial8250_omap_probe(struct platform_device *pdev)
+{
+	struct resource *regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	struct resource *irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	struct serial8250_omap_priv *priv;
+	struct uart_8250_port up;
+	int ret;
+	void __iomem *membase;
+
+	if (!regs || !irq) {
+		dev_err(&pdev->dev, "missing registers or irq\n");
+		return -EINVAL;
+	}
+
+	priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv) {
+		dev_err(&pdev->dev, "unable to allocate private data\n");
+		return -ENOMEM;
+	}
+	membase = devm_ioremap_nocache(&pdev->dev, regs->start,
+			resource_size(regs));
+	if (!membase)
+		return -ENODEV;
+
+	memset(&up, 0, sizeof(up));
+	up.port.dev = &pdev->dev;
+	up.port.mapbase = regs->start;
+	up.port.membase = membase;
+	up.port.irq = irq->start;
+	/*
+	 * It claims to be 16C750 compatible however it is a little different.
+	 * It has EFR and has no FCR7_64byte bit. The AFE which it claims to is
+	 * enabled via EFR instead of MCR.
+	 */
+	up.port.type = PORT_OMAP_16750;
+	up.port.iotype = UPIO_MEM32;
+	up.port.flags = UPF_BOOT_AUTOCONF | UPF_FIXED_PORT | UPF_FIXED_TYPE;
+	up.port.private_data = priv;
+
+	up.port.regshift = 2;
+	up.port.fifosize = 64;
+
+	up.port.set_termios = omap_8250_set_termios;
+	up.port.pm = omap_8250_pm;
+//	up.port.startup = omap_8250_startup;
+	/*
+	 * XXX
+	 * throttle
+	 * unthrottle
+	 */
+
+	if (pdev->dev.of_node) {
+		up.port.line = of_alias_get_id(pdev->dev.of_node, "serial");
+		of_property_read_u32(pdev->dev.of_node, "clock-frequency",
+				&up.port.uartclk);
+	} else {
+		up.port.line = pdev->id;
+	}
+
+	if (up.port.line < 0) {
+		dev_err(&pdev->dev, "failed to get alias/pdev id, errno %d\n",
+				up.port.line);
+		ret = -ENODEV;
+		/*XXX*/
+		BUG();
+	}
+	if (!up.port.uartclk) {
+		up.port.uartclk = DEFAULT_CLK_SPEED;
+		dev_warn(&pdev->dev,
+				"No clock speed specified: using default: %d\n",
+				DEFAULT_CLK_SPEED);
+	}
+
+	priv->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
+	priv->calc_latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
+	pm_qos_add_request(&priv->pm_qos_request,
+			PM_QOS_CPU_DMA_LATENCY, priv->latency);
+	INIT_WORK(&priv->qos_work, serial_omap_uart_qos_work);
+
+	device_init_wakeup(&pdev->dev, true);
+	pm_runtime_use_autosuspend(&pdev->dev);
+	pm_runtime_set_autosuspend_delay(&pdev->dev, -1);
+
+	pm_runtime_irq_safe(&pdev->dev);
+	pm_runtime_enable(&pdev->dev);
+
+	pm_runtime_get_sync(&pdev->dev);
+
+	omap_serial_fill_features_erratas(&up, priv);
+
+	ret = serial8250_register_8250_port(&up);
+	if (ret < 0) {
+		dev_err(&pdev->dev, "unable to register 8250 port\n");
+		goto err;
+	}
+	priv->line = ret;
+	platform_set_drvdata(pdev, priv);
+	pm_runtime_mark_last_busy(&pdev->dev);
+	pm_runtime_put_autosuspend(&pdev->dev);
+	return 0;
+err:
+	pm_runtime_put(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	return ret;
+}
+
+static int serial8250_omap_remove(struct platform_device *pdev)
+{
+	struct serial8250_omap_priv *priv = platform_get_drvdata(pdev);
+
+	pm_runtime_put_sync(&pdev->dev);
+	pm_runtime_disable(&pdev->dev);
+	serial8250_unregister_port(priv->line);
+	pm_qos_remove_request(&priv->pm_qos_request);
+	device_init_wakeup(&pdev->dev, false);
+	return 0;
+}
+
+#ifdef CONFIG_PM_SLEEP
+static int serial_omap_prepare(struct device *dev)
+{
+	struct serial8250_omap_priv *priv = dev_get_drvdata(dev);
+
+	priv->is_suspending = true;
+	return 0;
+}
+
+static void serial_omap_complete(struct device *dev)
+{
+	struct serial8250_omap_priv *priv = dev_get_drvdata(dev);
+
+	priv->is_suspending = false;
+}
+
+static inline void serial_omap_enable_wakeirq(struct serial8250_omap_priv *priv,
+		bool enable)
+{
+	if (!priv->wakeirq)
+		return;
+
+	if (enable)
+		enable_irq(priv->wakeirq);
+	else
+		disable_irq_nosync(priv->wakeirq);
+}
+
+static void serial_omap_enable_wakeup(struct serial8250_omap_priv *priv,
+		bool enable)
+{
+	if (enable == priv->wakeups_enabled)
+		return;
+
+	serial_omap_enable_wakeirq(priv, enable);
+	priv->wakeups_enabled = enable;
+
+	/* XXX
+	 * So
+	 *   omap_uart_enable_wakeup(dev, enable);
+	 * could be assigned here but my
+	 *   pdata->enable_wakeup(up->dev, enable);
+	 * NULL here…
+	 */
+}
+
+static int serial_omap_suspend(struct device *dev)
+{
+	struct serial8250_omap_priv *priv = dev_get_drvdata(dev);
+
+	serial8250_suspend_port(priv->line);
+	flush_work(&priv->qos_work);
+
+	if (device_may_wakeup(dev))
+		serial_omap_enable_wakeup(priv, true);
+	else
+		serial_omap_enable_wakeup(priv, false);
+	return 0;
+}
+
+static int serial_omap_resume(struct device *dev)
+{
+	struct serial8250_omap_priv *priv = dev_get_drvdata(dev);
+
+	if (device_may_wakeup(dev))
+		serial_omap_enable_wakeup(priv, false);
+
+	serial8250_resume_port(priv->line);
+	return 0;
+}
+#else
+#define serial_omap_prepare NULL
+#define serial_omap_complete NULL
+#endif
+
+#ifdef CONFIG_PM_RUNTIME
+static int serial_omap_get_context_loss_count(struct serial8250_omap_priv *priv)
+{
+	/*
+	 * XXX
+	 * Is this still used? I have here a NULL pointer on my am335x-evm
+	 */
+	return -EINVAL;
+}
+
+static int serial_omap_runtime_suspend(struct device *dev)
+{
+	struct serial8250_omap_priv *priv = dev_get_drvdata(dev);
+
+	/*
+	 * When using 'no_console_suspend', the console UART must not be
+	 * suspended. Since driver suspend is managed by runtime suspend,
+	 * preventing runtime suspend (by returning error) will keep device
+	 * active during suspend.
+	 */
+	if (priv->is_suspending && !console_suspend_enabled)
+		/*
+		 *  XXX Since I have no idea how to get to port right now it is
+		 *  just assumed true for uarts…
+		 *	&& uart_console(&up->port))
+		 */
+		return -EBUSY;
+
+	priv->context_loss_cnt = serial_omap_get_context_loss_count(priv);
+
+	serial_omap_enable_wakeup(priv, true);
+
+	priv->latency = PM_QOS_CPU_DMA_LAT_DEFAULT_VALUE;
+	schedule_work(&priv->qos_work);
+	return 0;
+}
+
+static void serial_omap_restore_context(struct serial8250_omap_priv *priv)
+{
+	struct uart_8250_port *up;
+
+	up = serial8250_get_port(priv->line);
+
+	if (priv->habit & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_8250_mdr1_errataset(up, UART_OMAP_MDR1_DISABLE);
+	else
+		serial_out(up, UART_OMAP_MDR1, UART_OMAP_MDR1_DISABLE);
+
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); /* Config B mode */
+	serial_out(up, UART_EFR, UART_EFR_ECB);
+	serial_out(up, UART_LCR, 0x0); /* Operational mode */
+	serial_out(up, UART_IER, 0x0);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); /* Config B mode */
+
+	serial_dl_write(up, priv->quot);
+
+	serial_out(up, UART_LCR, 0x0); /* Operational mode */
+	serial_out(up, UART_IER, up->ier);
+	serial_out(up, UART_FCR, priv->fcr);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_A);
+	serial_out(up, UART_MCR, up->mcr);
+	serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B); /* Config B mode */
+	serial_out(up, UART_OMAP_SCR, priv->scr);
+	serial_out(up, UART_EFR, priv->efr);
+	serial_out(up, UART_LCR, up->lcr);
+	if (priv->habit & UART_ERRATA_i202_MDR1_ACCESS)
+		omap_8250_mdr1_errataset(up, priv->mdr1);
+	else
+		serial_out(up, UART_OMAP_MDR1, priv->mdr1);
+	/*
+	 * XXX
+	 * serial_out(up, UART_OMAP_WER, up->wer);
+	 */
+}
+
+static int serial_omap_runtime_resume(struct device *dev)
+{
+	struct serial8250_omap_priv *priv = dev_get_drvdata(dev);
+	int loss_cnt = serial_omap_get_context_loss_count(priv);
+
+	serial_omap_enable_wakeup(priv, false);
+
+	if (loss_cnt < 0) {
+		dev_dbg(dev, "serial_omap_get_context_loss_count failed : %d\n",
+				loss_cnt);
+		serial_omap_restore_context(priv);
+	} else if (priv->context_loss_cnt != loss_cnt) {
+		serial_omap_restore_context(priv);
+	}
+	priv->latency = priv->calc_latency;
+	schedule_work(&priv->qos_work);
+
+	return 0;
+}
+#endif
+
+static const struct dev_pm_ops serial8250_omap_dev_pm_ops = {
+	SET_SYSTEM_SLEEP_PM_OPS(serial_omap_suspend, serial_omap_resume)
+	SET_RUNTIME_PM_OPS(serial_omap_runtime_suspend,
+			serial_omap_runtime_resume, NULL)
+	.prepare        = serial_omap_prepare,
+	.complete       = serial_omap_complete,
+};
+
+static const struct of_device_id serial8250_omap_dt_ids[] = {
+	{ .compatible = "ti,omap2-uart" },
+	{ .compatible = "ti,omap3-uart" },
+	{ .compatible = "ti,omap4-uart" },
+	{},
+};
+MODULE_DEVICE_TABLE(of, serial8250_omap_dt_ids);
+
+static struct platform_driver serial8250_omap_platform_driver = {
+	.driver = {
+		.name		= "serial8250-omap",
+		.pm		= &serial8250_omap_dev_pm_ops,
+		.of_match_table = serial8250_omap_dt_ids,
+		.owner		= THIS_MODULE,
+	},
+	.probe			= serial8250_omap_probe,
+	.remove			= serial8250_omap_remove,
+};
+module_platform_driver(serial8250_omap_platform_driver);
+
+MODULE_AUTHOR("Sebastian Andrzej Siewior");
+MODULE_DESCRIPTION("OMAP 8250 Driver");
+MODULE_LICENSE("GPL v2");
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index 349ee59..7a5073b 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -298,3 +298,12 @@ config SERIAL_8250_RT288X
 	  If you have a Ralink RT288x/RT305x SoC based board and want to use the
 	  serial port, say Y to this option. The driver can handle up to 2 serial
 	  ports. If unsure, say N.
+
+config SERIAL_8250_OMAP
+	tristate "Support for OMAP internal UART (8250 based driver)"
+	depends on SERIAL_8250 && ARCH_OMAP2PLUS
+	help
+	  If you have a machine based on an Texas Instruments OMAP CPU you
+	  can enable its onboard serial ports by enabling this option.
+
+	  This driver is in early stage and uses ttyS instead of ttyO.
diff --git a/drivers/tty/serial/8250/Makefile b/drivers/tty/serial/8250/Makefile
index 36d68d0..4bac392 100644
--- a/drivers/tty/serial/8250/Makefile
+++ b/drivers/tty/serial/8250/Makefile
@@ -20,3 +20,4 @@ obj-$(CONFIG_SERIAL_8250_HUB6)		+= 8250_hub6.o
 obj-$(CONFIG_SERIAL_8250_FSL)		+= 8250_fsl.o
 obj-$(CONFIG_SERIAL_8250_DW)		+= 8250_dw.o
 obj-$(CONFIG_SERIAL_8250_EM)		+= 8250_em.o
+obj-$(CONFIG_SERIAL_8250_OMAP)		+= 8250_omap.o
diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
index 5820269..74f9b11 100644
--- a/include/uapi/linux/serial_core.h
+++ b/include/uapi/linux/serial_core.h
@@ -54,7 +54,8 @@
 #define PORT_ALTR_16550_F32 26	/* Altera 16550 UART with 32 FIFOs */
 #define PORT_ALTR_16550_F64 27	/* Altera 16550 UART with 64 FIFOs */
 #define PORT_ALTR_16550_F128 28 /* Altera 16550 UART with 128 FIFOs */
-#define PORT_MAX_8250	28	/* max port ID */
+#define PORT_OMAP_16750	29	/* TI's OMAP internal 16C750 compatible UART */
+#define PORT_MAX_8250	29	/* max port ID */
 
 /*
  * ARM specific type numbers.  These are not currently guaranteed
-- 
2.0.0

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