Re: [PATCH v5 10/14] serial: pic32_uart: Add PIC32 UART driver

[Joshua Henderson <joshua.henderson@microchip.com>]

Hi Greg and Jiri,

Ping!  Need an ack for this or pull it upstream.

On 01/13/2016 06:15 PM, Joshua Henderson wrote:
> From: Andrei Pistirica <andrei.pistirica@microchip.com>
> 
> This adds UART and a serial console driver for Microchip PIC32 class
> devices.
> 
> Signed-off-by: Andrei Pistirica <andrei.pistirica@microchip.com>
> Signed-off-by: Joshua Henderson <joshua.henderson@microchip.com>
> Cc: Ralf Baechle <ralf@linux-mips.org>
> ---
> Changes since v4:
> 	- Clean up irq alloc on failure
> 	- Fix rework regression with handling failure in probe
> Changes since v3: None
> Changes since v2:
> 	- Use dynamic major/minor and ttyPIC* instead of ttyS*
> 	- Remove unused header files
> 	- Refactor register read/write functions
> 	- Reorder arguments to readl/writel functions
> 	- Add missing initializations to termios
> 	- Fix clk enable/disable mismatch
> Changes since v1:
> 	- Rename all instances of "USART" to "UART"
> 	- Remove unecessary uart-has-rtscts support
> ---
>  drivers/tty/serial/Kconfig       |   21 +
>  drivers/tty/serial/Makefile      |    1 +
>  drivers/tty/serial/pic32_uart.c  |  960 ++++++++++++++++++++++++++++++++++++++
>  drivers/tty/serial/pic32_uart.h  |  126 +++++
>  include/uapi/linux/serial_core.h |    3 +
>  5 files changed, 1111 insertions(+)
>  create mode 100644 drivers/tty/serial/pic32_uart.c
>  create mode 100644 drivers/tty/serial/pic32_uart.h
> 
> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
> index f38beb2..8853b1e 100644
> --- a/drivers/tty/serial/Kconfig
> +++ b/drivers/tty/serial/Kconfig
> @@ -901,6 +901,27 @@ 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
> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
> index 5ab4111..bc5e354 100644
> --- a/drivers/tty/serial/Makefile
> +++ b/drivers/tty/serial/Makefile
> @@ -93,6 +93,7 @@ obj-$(CONFIG_SERIAL_CONEXANT_DIGICOLOR)	+= digicolor-usart.o
>  obj-$(CONFIG_SERIAL_MEN_Z135)	+= men_z135_uart.o
>  obj-$(CONFIG_SERIAL_SPRD) += sprd_serial.o
>  obj-$(CONFIG_SERIAL_STM32)	+= stm32-usart.o
> +obj-$(CONFIG_SERIAL_PIC32)	+= pic32_uart.o
>  
>  # GPIOLIB helpers for modem control lines
>  obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
> diff --git a/drivers/tty/serial/pic32_uart.c b/drivers/tty/serial/pic32_uart.c
> new file mode 100644
> index 0000000..62a43bf
> --- /dev/null
> +++ b/drivers/tty/serial/pic32_uart.c
> @@ -0,0 +1,960 @@
> +/*
> + * 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");
> diff --git a/drivers/tty/serial/pic32_uart.h b/drivers/tty/serial/pic32_uart.h
> new file mode 100644
> index 0000000..ec379da
> --- /dev/null
> +++ b/drivers/tty/serial/pic32_uart.h
> @@ -0,0 +1,126 @@
> +/*
> + * 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__ */
> diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
> index 93ba148..9df0a98 100644
> --- a/include/uapi/linux/serial_core.h
> +++ b/include/uapi/linux/serial_core.h
> @@ -261,4 +261,7 @@
>  /* STM32 USART */
>  #define PORT_STM32	113
>  
> +/* Microchip PIC32 UART */
> +#define PORT_PIC32	114
> +
>  #endif /* _UAPILINUX_SERIAL_CORE_H */
>