serial: pic32_uart: Add PIC32 UART driver

This adds UART and a serial console driver for Microchip PIC32 class
devices.

[ralf@linux-mips.org: Resolved merge conflict.]
Signed-off-by: Andrei Pistirica <andrei.pistirica@microchip.com>
Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
Reviewed-by: Alan Cox <alan@linux.intel.com>
Acked-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Jiri Slaby <jslaby@suse.com>
Cc: linux-kernel@vger.kernel.org
Cc: linux-mips@linux-mips.org
Cc: linux-serial@vger.kernel.org
Cc: linux-api@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12101/Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

drivers/tty/serial/Kconfig

@@ -900,6 +900,27 @@ config SERIAL_SGI_L1_CONSOLE
 		controller serial port as your console (you want this!),
 		say Y.  Otherwise, say N.
 
+config SERIAL_PIC32
+	tristate "Microchip PIC32 serial support"
+	depends on MACH_PIC32
+	select SERIAL_CORE
+	help
+	  If you have a PIC32, this driver supports the serial ports.
+
+	  Say Y or M to use PIC32 serial ports, otherwise say N. Note that
+	  to use a serial port as a console, this must be included in kernel and
+	  not as a module.
+
+config SERIAL_PIC32_CONSOLE
+	bool "PIC32 serial console support"
+	depends on SERIAL_PIC32
+	select SERIAL_CORE_CONSOLE
+	help
+	  If you have a PIC32, this driver supports the putting a console on one
+	  of the serial ports.
+
+	  Say Y to use the PIC32 console, otherwise say N.
+
 config SERIAL_MPC52xx
 	tristate "Freescale MPC52xx/MPC512x family PSC serial support"
 	depends on PPC_MPC52xx || PPC_MPC512x

drivers/tty/serial/Makefile

@@ -91,6 +91,7 @@ obj-$(CONFIG_SERIAL_MEN_Z135)	+= men_z135_uart.o
 obj-$(CONFIG_SERIAL_SPRD) += sprd_serial.o
 obj-$(CONFIG_SERIAL_STM32)	+= stm32-usart.o
 obj-$(CONFIG_SERIAL_MVEBU_UART)	+= mvebu-uart.o
+obj-$(CONFIG_SERIAL_PIC32)	+= pic32_uart.o
 
 # GPIOLIB helpers for modem control lines
 obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o

drivers/tty/serial/pic32_uart.c

+/*
+ * PIC32 Integrated Serial Driver.
+ *
+ * Copyright (C) 2015 Microchip Technology, Inc.
+ *
+ * Authors:
+ *   Sorin-Andrei Pistirica <andrei.pistirica@microchip.com>
+ *
+ * Licensed under GPLv2 or later.
+ */
+
+#include <linux/kernel.h>
+#include <linux/platform_device.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/of_irq.h>
+#include <linux/of_gpio.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/console.h>
+#include <linux/clk.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/serial_core.h>
+#include <linux/delay.h>
+
+#include <asm/mach-pic32/pic32.h>
+#include "pic32_uart.h"
+
+/* UART name and device definitions */
+#define PIC32_DEV_NAME		"pic32-uart"
+#define PIC32_MAX_UARTS		6
+#define PIC32_SDEV_NAME		"ttyPIC"
+
+/* pic32_sport pointer for console use */
+static struct pic32_sport *pic32_sports[PIC32_MAX_UARTS];
+
+static inline void pic32_wait_deplete_txbuf(struct pic32_sport *sport)
+{
+	/* wait for tx empty, otherwise chars will be lost or corrupted */
+	while (!(pic32_uart_readl(sport, PIC32_UART_STA) & PIC32_UART_STA_TRMT))
+		udelay(1);
+}
+
+static inline int pic32_enable_clock(struct pic32_sport *sport)
+{
+	int ret = clk_prepare_enable(sport->clk);
+
+	if (ret)
+		return ret;
+
+	sport->ref_clk++;
+	return 0;
+}
+
+static inline void pic32_disable_clock(struct pic32_sport *sport)
+{
+	sport->ref_clk--;
+	clk_disable_unprepare(sport->clk);
+}
+
+/* serial core request to check if uart tx buffer is empty */
+static unsigned int pic32_uart_tx_empty(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	u32 val = pic32_uart_readl(sport, PIC32_UART_STA);
+
+	return (val & PIC32_UART_STA_TRMT) ? 1 : 0;
+}
+
+/* serial core request to set UART outputs */
+static void pic32_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	/* set loopback mode */
+	if (mctrl & TIOCM_LOOP)
+		pic32_uart_writel(sport, PIC32_SET(PIC32_UART_MODE),
+					PIC32_UART_MODE_LPBK);
+	else
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_LPBK);
+}
+
+/* get the state of CTS input pin for this port */
+static unsigned int get_cts_state(struct pic32_sport *sport)
+{
+	/* read and invert UxCTS */
+	if (gpio_is_valid(sport->cts_gpio))
+		return !gpio_get_value(sport->cts_gpio);
+
+	return 1;
+}
+
+/* serial core request to return the state of misc UART input pins */
+static unsigned int pic32_uart_get_mctrl(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	unsigned int mctrl = 0;
+
+	if (!sport->hw_flow_ctrl)
+		mctrl |= TIOCM_CTS;
+	else if (get_cts_state(sport))
+		mctrl |= TIOCM_CTS;
+
+	/* DSR and CD are not supported in PIC32, so return 1
+	 * RI is not supported in PIC32, so return 0
+	 */
+	mctrl |= TIOCM_CD;
+	mctrl |= TIOCM_DSR;
+
+	return mctrl;
+}
+
+/* stop tx and start tx are not called in pairs, therefore a flag indicates
+ * the status of irq to control the irq-depth.
+ */
+static inline void pic32_uart_irqtxen(struct pic32_sport *sport, u8 en)
+{
+	if (en && !tx_irq_enabled(sport)) {
+		enable_irq(sport->irq_tx);
+		tx_irq_enabled(sport) = 1;
+	} else if (!en && tx_irq_enabled(sport)) {
+		/* use disable_irq_nosync() and not disable_irq() to avoid self
+		 * imposed deadlock by not waiting for irq handler to end,
+		 * since this callback is called from interrupt context.
+		 */
+		disable_irq_nosync(sport->irq_tx);
+		tx_irq_enabled(sport) = 0;
+	}
+}
+
+/* serial core request to disable tx ASAP (used for flow control) */
+static void pic32_uart_stop_tx(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	if (!(pic32_uart_readl(sport, PIC32_UART_MODE) & PIC32_UART_MODE_ON))
+		return;
+
+	if (!(pic32_uart_readl(sport, PIC32_UART_STA) & PIC32_UART_STA_UTXEN))
+		return;
+
+	/* wait for tx empty */
+	pic32_wait_deplete_txbuf(sport);
+
+	pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA),
+				PIC32_UART_STA_UTXEN);
+	pic32_uart_irqtxen(sport, 0);
+}
+
+/* serial core request to (re)enable tx */
+static void pic32_uart_start_tx(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	pic32_uart_irqtxen(sport, 1);
+	pic32_uart_writel(sport, PIC32_SET(PIC32_UART_STA),
+				PIC32_UART_STA_UTXEN);
+}
+
+/* serial core request to stop rx, called before port shutdown */
+static void pic32_uart_stop_rx(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	/* disable rx interrupts */
+	disable_irq(sport->irq_rx);
+
+	/* receiver Enable bit OFF */
+	pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA),
+				PIC32_UART_STA_URXEN);
+}
+
+/* serial core request to start/stop emitting break char */
+static void pic32_uart_break_ctl(struct uart_port *port, int ctl)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	if (ctl)
+		pic32_uart_writel(sport, PIC32_SET(PIC32_UART_STA),
+					PIC32_UART_STA_UTXBRK);
+	else
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA),
+					PIC32_UART_STA_UTXBRK);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/* get port type in string format */
+static const char *pic32_uart_type(struct uart_port *port)
+{
+	return (port->type == PORT_PIC32) ? PIC32_DEV_NAME : NULL;
+}
+
+/* read all chars in rx fifo and send them to core */
+static void pic32_uart_do_rx(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	struct tty_port *tty;
+	unsigned int max_count;
+
+	/* limit number of char read in interrupt, should not be
+	 * higher than fifo size anyway since we're much faster than
+	 * serial port
+	 */
+	max_count = PIC32_UART_RX_FIFO_DEPTH;
+
+	spin_lock(&port->lock);
+
+	tty = &port->state->port;
+
+	do {
+		u32 sta_reg, c;
+		char flag;
+
+		/* get overrun/fifo empty information from status register */
+		sta_reg = pic32_uart_readl(sport, PIC32_UART_STA);
+		if (unlikely(sta_reg & PIC32_UART_STA_OERR)) {
+
+			/* fifo reset is required to clear interrupt */
+			pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA),
+						PIC32_UART_STA_OERR);
+
+			port->icount.overrun++;
+			tty_insert_flip_char(tty, 0, TTY_OVERRUN);
+		}
+
+		/* Can at least one more character can be read? */
+		if (!(sta_reg & PIC32_UART_STA_URXDA))
+			break;
+
+		/* read the character and increment the rx counter */
+		c = pic32_uart_readl(sport, PIC32_UART_RX);
+
+		port->icount.rx++;
+		flag = TTY_NORMAL;
+		c &= 0xff;
+
+		if (unlikely((sta_reg & PIC32_UART_STA_PERR) ||
+			     (sta_reg & PIC32_UART_STA_FERR))) {
+
+			/* do stats first */
+			if (sta_reg & PIC32_UART_STA_PERR)
+				port->icount.parity++;
+			if (sta_reg & PIC32_UART_STA_FERR)
+				port->icount.frame++;
+
+			/* update flag wrt read_status_mask */
+			sta_reg &= port->read_status_mask;
+
+			if (sta_reg & PIC32_UART_STA_FERR)
+				flag = TTY_FRAME;
+			if (sta_reg & PIC32_UART_STA_PERR)
+				flag = TTY_PARITY;
+		}
+
+		if (uart_handle_sysrq_char(port, c))
+			continue;
+
+		if ((sta_reg & port->ignore_status_mask) == 0)
+			tty_insert_flip_char(tty, c, flag);
+
+	} while (--max_count);
+
+	spin_unlock(&port->lock);
+
+	tty_flip_buffer_push(tty);
+}
+
+/* fill tx fifo with chars to send, stop when fifo is about to be full
+ * or when all chars have been sent.
+ */
+static void pic32_uart_do_tx(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned int max_count = PIC32_UART_TX_FIFO_DEPTH;
+
+	if (port->x_char) {
+		pic32_uart_writel(sport, PIC32_UART_TX, port->x_char);
+		port->icount.tx++;
+		port->x_char = 0;
+		return;
+	}
+
+	if (uart_tx_stopped(port)) {
+		pic32_uart_stop_tx(port);
+		return;
+	}
+
+	if (uart_circ_empty(xmit))
+		goto txq_empty;
+
+	/* keep stuffing chars into uart tx buffer
+	 * 1) until uart fifo is full
+	 * or
+	 * 2) until the circ buffer is empty
+	 * (all chars have been sent)
+	 * or
+	 * 3) until the max count is reached
+	 * (prevents lingering here for too long in certain cases)
+	 */
+	while (!(PIC32_UART_STA_UTXBF &
+		pic32_uart_readl(sport, PIC32_UART_STA))) {
+		unsigned int c = xmit->buf[xmit->tail];
+
+		pic32_uart_writel(sport, PIC32_UART_TX, c);
+
+		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
+		port->icount.tx++;
+		if (uart_circ_empty(xmit))
+			break;
+		if (--max_count == 0)
+			break;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (uart_circ_empty(xmit))
+		goto txq_empty;
+
+	return;
+
+txq_empty:
+	pic32_uart_irqtxen(sport, 0);
+}
+
+/* RX interrupt handler */
+static irqreturn_t pic32_uart_rx_interrupt(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+
+	pic32_uart_do_rx(port);
+
+	return IRQ_HANDLED;
+}
+
+/* TX interrupt handler */
+static irqreturn_t pic32_uart_tx_interrupt(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+	pic32_uart_do_tx(port);
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+/* FAULT interrupt handler */
+static irqreturn_t pic32_uart_fault_interrupt(int irq, void *dev_id)
+{
+	/* do nothing: pic32_uart_do_rx() handles faults. */
+	return IRQ_HANDLED;
+}
+
+/* enable rx & tx operation on uart */
+static void pic32_uart_en_and_unmask(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	pic32_uart_writel(sport, PIC32_SET(PIC32_UART_STA),
+				PIC32_UART_STA_UTXEN | PIC32_UART_STA_URXEN);
+	pic32_uart_writel(sport, PIC32_SET(PIC32_UART_MODE),
+				PIC32_UART_MODE_ON);
+}
+
+/* disable rx & tx operation on uart */
+static void pic32_uart_dsbl_and_mask(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	/* wait for tx empty, otherwise chars will be lost or corrupted */
+	pic32_wait_deplete_txbuf(sport);
+
+	pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA),
+				PIC32_UART_STA_UTXEN | PIC32_UART_STA_URXEN);
+	pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+				PIC32_UART_MODE_ON);
+}
+
+/* serial core request to initialize uart and start rx operation */
+static int pic32_uart_startup(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	u32 dflt_baud = (port->uartclk / PIC32_UART_DFLT_BRATE / 16) - 1;
+	unsigned long flags;
+	int ret;
+
+	local_irq_save(flags);
+
+	ret = pic32_enable_clock(sport);
+	if (ret) {
+		local_irq_restore(flags);
+		goto out_done;
+	}
+
+	/* clear status and mode registers */
+	pic32_uart_writel(sport, PIC32_UART_MODE, 0);
+	pic32_uart_writel(sport, PIC32_UART_STA, 0);
+
+	/* disable uart and mask all interrupts */
+	pic32_uart_dsbl_and_mask(port);
+
+	/* set default baud */
+	pic32_uart_writel(sport, PIC32_UART_BRG, dflt_baud);
+
+	local_irq_restore(flags);
+
+	/* Each UART of a PIC32 has three interrupts therefore,
+	 * we setup driver to register the 3 irqs for the device.
+	 *
+	 * For each irq request_irq() is called with interrupt disabled.
+	 * And the irq is enabled as soon as we are ready to handle them.
+	 */
+	tx_irq_enabled(sport) = 0;
+
+	sport->irq_fault_name = kasprintf(GFP_KERNEL, "%s%d-fault",
+					  pic32_uart_type(port),
+					  sport->idx);
+	if (!sport->irq_fault_name) {
+		dev_err(port->dev, "%s: kasprintf err!", __func__);
+		ret = -ENOMEM;
+		goto out_done;
+	}
+	irq_set_status_flags(sport->irq_fault, IRQ_NOAUTOEN);
+	ret = request_irq(sport->irq_fault, pic32_uart_fault_interrupt,
+			  sport->irqflags_fault, sport->irq_fault_name, port);
+	if (ret) {
+		dev_err(port->dev, "%s: request irq(%d) err! ret:%d name:%s\n",
+			__func__, sport->irq_fault, ret,
+			pic32_uart_type(port));
+		goto out_f;
+	}
+
+	sport->irq_rx_name = kasprintf(GFP_KERNEL, "%s%d-rx",
+				       pic32_uart_type(port),
+				       sport->idx);
+	if (!sport->irq_rx_name) {
+		dev_err(port->dev, "%s: kasprintf err!", __func__);
+		kfree(sport->irq_fault_name);
+		ret = -ENOMEM;
+		goto out_f;
+	}
+	irq_set_status_flags(sport->irq_rx, IRQ_NOAUTOEN);
+	ret = request_irq(sport->irq_rx, pic32_uart_rx_interrupt,
+			  sport->irqflags_rx, sport->irq_rx_name, port);
+	if (ret) {
+		dev_err(port->dev, "%s: request irq(%d) err! ret:%d name:%s\n",
+			__func__, sport->irq_rx, ret,
+			pic32_uart_type(port));
+		goto out_r;
+	}
+
+	sport->irq_tx_name = kasprintf(GFP_KERNEL, "%s%d-tx",
+				       pic32_uart_type(port),
+				       sport->idx);
+	if (!sport->irq_tx_name) {
+		dev_err(port->dev, "%s: kasprintf err!", __func__);
+		ret = -ENOMEM;
+		goto out_r;
+	}
+	irq_set_status_flags(sport->irq_tx, IRQ_NOAUTOEN);
+	ret = request_irq(sport->irq_tx, pic32_uart_tx_interrupt,
+			  sport->irqflags_tx, sport->irq_tx_name, port);
+	if (ret) {
+		dev_err(port->dev, "%s: request irq(%d) err! ret:%d name:%s\n",
+			__func__, sport->irq_tx, ret,
+			pic32_uart_type(port));
+		goto out_t;
+	}
+
+	local_irq_save(flags);
+
+	/* set rx interrupt on first receive */
+	pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA),
+			PIC32_UART_STA_URXISEL1 | PIC32_UART_STA_URXISEL0);
+
+	/* set interrupt on empty */
+	pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_STA),
+			PIC32_UART_STA_UTXISEL1);
+
+	/* enable all interrupts and eanable uart */
+	pic32_uart_en_and_unmask(port);
+
+	enable_irq(sport->irq_rx);
+
+	return 0;
+
+out_t:
+	kfree(sport->irq_tx_name);
+	free_irq(sport->irq_tx, sport);
+out_r:
+	kfree(sport->irq_rx_name);
+	free_irq(sport->irq_rx, sport);
+out_f:
+	kfree(sport->irq_fault_name);
+	free_irq(sport->irq_fault, sport);
+out_done:
+	return ret;
+}
+
+/* serial core request to flush & disable uart */
+static void pic32_uart_shutdown(struct uart_port *port)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	unsigned long flags;
+
+	/* disable uart */
+	spin_lock_irqsave(&port->lock, flags);
+	pic32_uart_dsbl_and_mask(port);
+	spin_unlock_irqrestore(&port->lock, flags);
+	pic32_disable_clock(sport);
+
+	/* free all 3 interrupts for this UART */
+	free_irq(sport->irq_fault, port);
+	free_irq(sport->irq_tx, port);
+	free_irq(sport->irq_rx, port);
+}
+
+/* serial core request to change current uart setting */
+static void pic32_uart_set_termios(struct uart_port *port,
+				   struct ktermios *new,
+				   struct ktermios *old)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+	unsigned int baud;
+	unsigned int quot;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* disable uart and mask all interrupts while changing speed */
+	pic32_uart_dsbl_and_mask(port);
+
+	/* stop bit options */
+	if (new->c_cflag & CSTOPB)
+		pic32_uart_writel(sport, PIC32_SET(PIC32_UART_MODE),
+					PIC32_UART_MODE_STSEL);
+	else
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_STSEL);
+
+	/* parity options */
+	if (new->c_cflag & PARENB) {
+		if (new->c_cflag & PARODD) {
+			pic32_uart_writel(sport, PIC32_SET(PIC32_UART_MODE),
+					PIC32_UART_MODE_PDSEL1);
+			pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_PDSEL0);
+		} else {
+			pic32_uart_writel(sport, PIC32_SET(PIC32_UART_MODE),
+					PIC32_UART_MODE_PDSEL0);
+			pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_PDSEL1);
+		}
+	} else {
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_PDSEL1 |
+					PIC32_UART_MODE_PDSEL0);
+	}
+	/* if hw flow ctrl, then the pins must be specified in device tree */
+	if ((new->c_cflag & CRTSCTS) && sport->hw_flow_ctrl) {
+		/* enable hardware flow control */
+		pic32_uart_writel(sport, PIC32_SET(PIC32_UART_MODE),
+					PIC32_UART_MODE_UEN1);
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_UEN0);
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_RTSMD);
+	} else {
+		/* disable hardware flow control */
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_UEN1);
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_UEN0);
+		pic32_uart_writel(sport, PIC32_CLR(PIC32_UART_MODE),
+					PIC32_UART_MODE_RTSMD);
+	}
+
+	/* Always 8-bit */
+	new->c_cflag |= CS8;
+
+	/* Mark/Space parity is not supported */
+	new->c_cflag &= ~CMSPAR;
+
+	/* update baud */
+	baud = uart_get_baud_rate(port, new, old, 0, port->uartclk / 16);
+	quot = uart_get_divisor(port, baud) - 1;
+	pic32_uart_writel(sport, PIC32_UART_BRG, quot);
+	uart_update_timeout(port, new->c_cflag, baud);
+
+	if (tty_termios_baud_rate(new))
+		tty_termios_encode_baud_rate(new, baud, baud);
+
+	/* enable uart */
+	pic32_uart_en_and_unmask(port);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/* serial core request to claim uart iomem */
+static int pic32_uart_request_port(struct uart_port *port)
+{
+	struct platform_device *pdev = to_platform_device(port->dev);
+	struct resource *res_mem;
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (unlikely(!res_mem))
+		return -EINVAL;
+
+	if (!request_mem_region(port->mapbase, resource_size(res_mem),
+				"pic32_uart_mem"))
+		return -EBUSY;
+
+	port->membase = devm_ioremap_nocache(port->dev, port->mapbase,
+						resource_size(res_mem));
+	if (!port->membase) {
+		dev_err(port->dev, "Unable to map registers\n");
+		release_mem_region(port->mapbase, resource_size(res_mem));
+		return -ENOMEM;
+	}
+
+	return 0;
+}
+
+/* serial core request to release uart iomem */
+static void pic32_uart_release_port(struct uart_port *port)
+{
+	struct platform_device *pdev = to_platform_device(port->dev);
+	struct resource *res_mem;
+	unsigned int res_size;
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (unlikely(!res_mem))
+		return;
+	res_size = resource_size(res_mem);
+
+	release_mem_region(port->mapbase, res_size);
+}
+
+/* serial core request to do any port required auto-configuration */
+static void pic32_uart_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE) {
+		if (pic32_uart_request_port(port))
+			return;
+		port->type = PORT_PIC32;
+	}
+}
+
+/* serial core request to check that port information in serinfo are suitable */
+static int pic32_uart_verify_port(struct uart_port *port,
+				  struct serial_struct *serinfo)
+{
+	if (port->type != PORT_PIC32)
+		return -EINVAL;
+	if (port->irq != serinfo->irq)
+		return -EINVAL;
+	if (port->iotype != serinfo->io_type)
+		return -EINVAL;
+	if (port->mapbase != (unsigned long)serinfo->iomem_base)
+		return -EINVAL;
+
+	return 0;
+}
+
+/* serial core callbacks */
+static const struct uart_ops pic32_uart_ops = {
+	.tx_empty	= pic32_uart_tx_empty,
+	.get_mctrl	= pic32_uart_get_mctrl,
+	.set_mctrl	= pic32_uart_set_mctrl,
+	.start_tx	= pic32_uart_start_tx,
+	.stop_tx	= pic32_uart_stop_tx,
+	.stop_rx	= pic32_uart_stop_rx,
+	.break_ctl	= pic32_uart_break_ctl,
+	.startup	= pic32_uart_startup,
+	.shutdown	= pic32_uart_shutdown,
+	.set_termios	= pic32_uart_set_termios,
+	.type		= pic32_uart_type,
+	.release_port	= pic32_uart_release_port,
+	.request_port	= pic32_uart_request_port,
+	.config_port	= pic32_uart_config_port,
+	.verify_port	= pic32_uart_verify_port,
+};
+
+#ifdef CONFIG_SERIAL_PIC32_CONSOLE
+/* output given char */
+static void pic32_console_putchar(struct uart_port *port, int ch)
+{
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	if (!(pic32_uart_readl(sport, PIC32_UART_MODE) & PIC32_UART_MODE_ON))
+		return;
+
+	if (!(pic32_uart_readl(sport, PIC32_UART_STA) & PIC32_UART_STA_UTXEN))
+		return;
+
+	/* wait for tx empty */
+	pic32_wait_deplete_txbuf(sport);
+
+	pic32_uart_writel(sport, PIC32_UART_TX, ch & 0xff);
+}
+
+/* console core request to output given string */
+static void pic32_console_write(struct console *co, const char *s,
+				unsigned int count)
+{
+	struct pic32_sport *sport = pic32_sports[co->index];
+	struct uart_port *port = pic32_get_port(sport);
+
+	/* call uart helper to deal with \r\n */
+	uart_console_write(port, s, count, pic32_console_putchar);
+}
+
+/* console core request to setup given console, find matching uart
+ * port and setup it.
+ */
+static int pic32_console_setup(struct console *co, char *options)
+{
+	struct pic32_sport *sport;
+	struct uart_port *port = NULL;
+	int baud = 115200;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+	int ret = 0;
+
+	if (unlikely(co->index < 0 || co->index >= PIC32_MAX_UARTS))
+		return -ENODEV;
+
+	sport = pic32_sports[co->index];
+	if (!sport)
+		return -ENODEV;
+	port = pic32_get_port(sport);
+
+	ret = pic32_enable_clock(sport);
+	if (ret)
+		return ret;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver pic32_uart_driver;
+static struct console pic32_console = {
+	.name		= PIC32_SDEV_NAME,
+	.write		= pic32_console_write,
+	.device		= uart_console_device,
+	.setup		= pic32_console_setup,
+	.flags		= CON_PRINTBUFFER,
+	.index		= -1,
+	.data		= &pic32_uart_driver,
+};
+#define PIC32_SCONSOLE (&pic32_console)
+
+static int __init pic32_console_init(void)
+{
+	register_console(&pic32_console);
+	return 0;
+}
+console_initcall(pic32_console_init);
+
+static inline bool is_pic32_console_port(struct uart_port *port)
+{
+	return port->cons && port->cons->index == port->line;
+}
+
+/*
+ * Late console initialization.
+ */
+static int __init pic32_late_console_init(void)
+{
+	if (!(pic32_console.flags & CON_ENABLED))
+		register_console(&pic32_console);
+
+	return 0;
+}
+
+core_initcall(pic32_late_console_init);
+
+#else
+#define PIC32_SCONSOLE NULL
+#endif
+
+static struct uart_driver pic32_uart_driver = {
+	.owner			= THIS_MODULE,
+	.driver_name		= PIC32_DEV_NAME,
+	.dev_name		= PIC32_SDEV_NAME,
+	.nr			= PIC32_MAX_UARTS,
+	.cons			= PIC32_SCONSOLE,
+};
+
+static int pic32_uart_probe(struct platform_device *pdev)
+{
+	struct device_node *np = pdev->dev.of_node;
+	struct pic32_sport *sport;
+	int uart_idx = 0;
+	struct resource *res_mem;
+	struct uart_port *port;
+	int ret;
+
+	uart_idx = of_alias_get_id(np, "serial");
+	if (uart_idx < 0 || uart_idx >= PIC32_MAX_UARTS)
+		return -EINVAL;
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res_mem)
+		return -EINVAL;
+
+	sport = devm_kzalloc(&pdev->dev, sizeof(*sport), GFP_KERNEL);
+	if (!sport)
+		return -ENOMEM;
+
+	sport->idx		= uart_idx;
+	sport->irq_fault	= irq_of_parse_and_map(np, 0);
+	sport->irqflags_fault	= IRQF_NO_THREAD;
+	sport->irq_rx		= irq_of_parse_and_map(np, 1);
+	sport->irqflags_rx	= IRQF_NO_THREAD;
+	sport->irq_tx		= irq_of_parse_and_map(np, 2);
+	sport->irqflags_tx	= IRQF_NO_THREAD;
+	sport->clk		= devm_clk_get(&pdev->dev, NULL);
+	sport->cts_gpio		= -EINVAL;
+	sport->dev		= &pdev->dev;
+
+	/* Hardware flow control: gpios
+	 * !Note: Basically, CTS is needed for reading the status.
+	 */
+	sport->hw_flow_ctrl = false;
+	sport->cts_gpio = of_get_named_gpio(np, "cts-gpios", 0);
+	if (gpio_is_valid(sport->cts_gpio)) {
+		sport->hw_flow_ctrl = true;
+
+		ret = devm_gpio_request(sport->dev,
+					sport->cts_gpio, "CTS");
+		if (ret) {
+			dev_err(&pdev->dev,
+				"error requesting CTS GPIO\n");
+			goto err;
+		}
+
+		ret = gpio_direction_input(sport->cts_gpio);
+		if (ret) {
+			dev_err(&pdev->dev, "error setting CTS GPIO\n");
+			goto err;
+		}
+	}
+
+	pic32_sports[uart_idx] = sport;
+	port = &sport->port;
+	memset(port, 0, sizeof(*port));
+	port->iotype	= UPIO_MEM;
+	port->mapbase	= res_mem->start;
+	port->ops	= &pic32_uart_ops;
+	port->flags	= UPF_BOOT_AUTOCONF;
+	port->dev	= &pdev->dev;
+	port->fifosize	= PIC32_UART_TX_FIFO_DEPTH;
+	port->uartclk	= clk_get_rate(sport->clk);
+	port->line	= uart_idx;
+
+	ret = uart_add_one_port(&pic32_uart_driver, port);
+	if (ret) {
+		port->membase = NULL;
+		dev_err(port->dev, "%s: uart add port error!\n", __func__);
+		goto err;
+	}
+
+#ifdef CONFIG_SERIAL_PIC32_CONSOLE
+	if (is_pic32_console_port(port) &&
+	    (pic32_console.flags & CON_ENABLED)) {
+		/* The peripheral clock has been enabled by console_setup,
+		 * so disable it till the port is used.
+		 */
+		pic32_disable_clock(sport);
+	}
+#endif
+
+	platform_set_drvdata(pdev, port);
+
+	dev_info(&pdev->dev, "%s: uart(%d) driver initialized.\n",
+		 __func__, uart_idx);
+
+	return 0;
+err:
+	/* automatic unroll of sport and gpios */
+	return ret;
+}
+
+static int pic32_uart_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = platform_get_drvdata(pdev);
+	struct pic32_sport *sport = to_pic32_sport(port);
+
+	uart_remove_one_port(&pic32_uart_driver, port);
+	pic32_disable_clock(sport);
+	platform_set_drvdata(pdev, NULL);
+	pic32_sports[sport->idx] = NULL;
+
+	/* automatic unroll of sport and gpios */
+	return 0;
+}
+
+static const struct of_device_id pic32_serial_dt_ids[] = {
+	{ .compatible = "microchip,pic32mzda-uart" },
+	{ /* sentinel */ }
+};
+MODULE_DEVICE_TABLE(of, pic32_serial_dt_ids);
+
+static struct platform_driver pic32_uart_platform_driver = {
+	.probe		= pic32_uart_probe,
+	.remove		= pic32_uart_remove,
+	.driver		= {
+		.name	= PIC32_DEV_NAME,
+		.of_match_table	= of_match_ptr(pic32_serial_dt_ids),
+	},
+};
+
+static int __init pic32_uart_init(void)
+{
+	int ret;
+
+	ret = uart_register_driver(&pic32_uart_driver);
+	if (ret) {
+		pr_err("failed to register %s:%d\n",
+		       pic32_uart_driver.driver_name, ret);
+		return ret;
+	}
+
+	ret = platform_driver_register(&pic32_uart_platform_driver);
+	if (ret) {
+		pr_err("fail to register pic32 uart\n");
+		uart_unregister_driver(&pic32_uart_driver);
+	}
+
+	return ret;
+}
+arch_initcall(pic32_uart_init);
+
+static void __exit pic32_uart_exit(void)
+{
+#ifdef CONFIG_SERIAL_PIC32_CONSOLE
+	unregister_console(&pic32_console);
+#endif
+	platform_driver_unregister(&pic32_uart_platform_driver);
+	uart_unregister_driver(&pic32_uart_driver);
+}
+module_exit(pic32_uart_exit);
+
+MODULE_AUTHOR("Sorin-Andrei Pistirica <andrei.pistirica@microchip.com>");
+MODULE_DESCRIPTION("Microchip PIC32 integrated serial port driver");
+MODULE_LICENSE("GPL v2");

drivers/tty/serial/pic32_uart.h

+/*
+ * PIC32 Integrated Serial Driver.
+ *
+ * Copyright (C) 2015 Microchip Technology, Inc.
+ *
+ * Authors:
+ *   Sorin-Andrei Pistirica <andrei.pistirica@microchip.com>
+ *
+ * Licensed under GPLv2 or later.
+ */
+#ifndef __DT_PIC32_UART_H__
+#define __DT_PIC32_UART_H__
+
+#define PIC32_UART_DFLT_BRATE		(9600)
+#define PIC32_UART_TX_FIFO_DEPTH	(8)
+#define PIC32_UART_RX_FIFO_DEPTH	(8)
+
+#define PIC32_UART_MODE		0x00
+#define PIC32_UART_STA		0x10
+#define PIC32_UART_TX		0x20
+#define PIC32_UART_RX		0x30
+#define PIC32_UART_BRG		0x40
+
+struct pic32_console_opt {
+	int baud;
+	int parity;
+	int bits;
+	int flow;
+};
+
+/* struct pic32_sport - pic32 serial port descriptor
+ * @port: uart port descriptor
+ * @idx: port index
+ * @irq_fault: virtual fault interrupt number
+ * @irqflags_fault: flags related to fault irq
+ * @irq_fault_name: irq fault name
+ * @irq_rx: virtual rx interrupt number
+ * @irqflags_rx: flags related to rx irq
+ * @irq_rx_name: irq rx name
+ * @irq_tx: virtual tx interrupt number
+ * @irqflags_tx: : flags related to tx irq
+ * @irq_tx_name: irq tx name
+ * @cts_gpio: clear to send gpio
+ * @dev: device descriptor
+ **/
+struct pic32_sport {
+	struct uart_port port;
+	struct pic32_console_opt opt;
+	int idx;
+
+	int irq_fault;
+	int irqflags_fault;
+	const char *irq_fault_name;
+	int irq_rx;
+	int irqflags_rx;
+	const char *irq_rx_name;
+	int irq_tx;
+	int irqflags_tx;
+	const char *irq_tx_name;
+	u8 enable_tx_irq;
+
+	bool hw_flow_ctrl;
+	int cts_gpio;
+
+	int ref_clk;
+	struct clk *clk;
+
+	struct device *dev;
+};
+#define to_pic32_sport(c) container_of(c, struct pic32_sport, port)
+#define pic32_get_port(sport) (&sport->port)
+#define pic32_get_opt(sport) (&sport->opt)
+#define tx_irq_enabled(sport) (sport->enable_tx_irq)
+
+static inline void pic32_uart_writel(struct pic32_sport *sport,
+					u32 reg, u32 val)
+{
+	struct uart_port *port = pic32_get_port(sport);
+
+	__raw_writel(val, port->membase + reg);
+}
+
+static inline u32 pic32_uart_readl(struct pic32_sport *sport, u32 reg)
+{
+	struct uart_port *port = pic32_get_port(sport);
+
+	return	__raw_readl(port->membase + reg);
+}
+
+/* pic32 uart mode register bits */
+#define PIC32_UART_MODE_ON        BIT(15)
+#define PIC32_UART_MODE_FRZ       BIT(14)
+#define PIC32_UART_MODE_SIDL      BIT(13)
+#define PIC32_UART_MODE_IREN      BIT(12)
+#define PIC32_UART_MODE_RTSMD     BIT(11)
+#define PIC32_UART_MODE_RESV1     BIT(10)
+#define PIC32_UART_MODE_UEN1      BIT(9)
+#define PIC32_UART_MODE_UEN0      BIT(8)
+#define PIC32_UART_MODE_WAKE      BIT(7)
+#define PIC32_UART_MODE_LPBK      BIT(6)
+#define PIC32_UART_MODE_ABAUD     BIT(5)
+#define PIC32_UART_MODE_RXINV     BIT(4)
+#define PIC32_UART_MODE_BRGH      BIT(3)
+#define PIC32_UART_MODE_PDSEL1    BIT(2)
+#define PIC32_UART_MODE_PDSEL0    BIT(1)
+#define PIC32_UART_MODE_STSEL     BIT(0)
+
+/* pic32 uart status register bits */
+#define PIC32_UART_STA_UTXISEL1   BIT(15)
+#define PIC32_UART_STA_UTXISEL0   BIT(14)
+#define PIC32_UART_STA_UTXINV     BIT(13)
+#define PIC32_UART_STA_URXEN      BIT(12)
+#define PIC32_UART_STA_UTXBRK     BIT(11)
+#define PIC32_UART_STA_UTXEN      BIT(10)
+#define PIC32_UART_STA_UTXBF      BIT(9)
+#define PIC32_UART_STA_TRMT       BIT(8)
+#define PIC32_UART_STA_URXISEL1   BIT(7)
+#define PIC32_UART_STA_URXISEL0   BIT(6)
+#define PIC32_UART_STA_ADDEN      BIT(5)
+#define PIC32_UART_STA_RIDLE      BIT(4)
+#define PIC32_UART_STA_PERR       BIT(3)
+#define PIC32_UART_STA_FERR       BIT(2)
+#define PIC32_UART_STA_OERR       BIT(1)
+#define PIC32_UART_STA_URXDA      BIT(0)
+
+#endif /* __DT_PIC32_UART_H__ */

include/uapi/linux/serial_core.h

@@ -264,4 +264,7 @@
 /* MVEBU UART */
 #define PORT_MVEBU	114
 
+/* Microchip PIC32 UART */
+#define PORT_PIC32	114
+
 #endif /* _UAPILINUX_SERIAL_CORE_H */