Message-ID: <54BE45EA.3030308@gmail.com>
Date:	Tue, 20 Jan 2015 20:11:22 +0800
From:	Orson Zhai <orsonzhai@...il.com>
To:	Peter Hurley <peter@...leysoftware.com>,
	Chunyan Zhang <chunyan.zhang@...eadtrum.com>
CC:	gregkh@...uxfoundation.org, mark.rutland@....com, arnd@...db.de,
	gnomes@...rguk.ukuu.org.uk, broonie@...nel.org, robh+dt@...nel.org,
	pawel.moll@....com, ijc+devicetree@...lion.org.uk,
	galak@...eaurora.org, will.deacon@....com, catalin.marinas@....com,
	jslaby@...e.cz, jason@...edaemon.net, heiko@...ech.de,
	florian.vaussard@...l.ch, andrew@...n.ch, rrichter@...ium.com,
	hytszk@...il.com, grant.likely@...aro.org, antonynpavlov@...il.com,
	Joel.Schopp@....com, Suravee.Suthikulpanit@....com,
	shawn.guo@...aro.org, lea.yan@...aro.org,
	jorge.ramirez-ortiz@...aro.org, lee.jones@...aro.org,
	geng.ren@...eadtrum.com, zhizhou.zhang@...eadtrum.com,
	lanqing.liu@...eadtrum.com, zhang.lyra@...il.com,
	wei.qiao@...eadtrum.com, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org, linux-serial@...r.kernel.org
Subject: Re: [PATCH v5 5/5] tty/serial: Add Spreadtrum sc9836-uart driver
 support

Hi, Peter,

Thank you for reviewing our code!
Some discussion below.

On 2015年01月16日 23:20, Peter Hurley wrote:
> On 01/16/2015 05:00 AM, Chunyan Zhang wrote:
>> Add a full sc9836-uart driver for SC9836 SoC which is based on the
>> spreadtrum sharkl64 platform.
>> This driver also support earlycon.
>> This patch also replaced the spaces between the macros and their
>> values with the tabs in serial_core.h
> The locking doesn't look correct. Specific notations below.
>
>> Signed-off-by: Chunyan Zhang <chunyan.zhang@...eadtrum.com>
>> Signed-off-by: Orson Zhai <orson.zhai@...eadtrum.com>
>> Originally-by: Lanqing Liu <lanqing.liu@...eadtrum.com>
>> ---
>>   drivers/tty/serial/Kconfig       |   18 +
>>   drivers/tty/serial/Makefile      |    1 +
>>   drivers/tty/serial/sprd_serial.c |  772 ++++++++++++++++++++++++++++++++++++++
>>   include/uapi/linux/serial_core.h |    3 +
>>   4 files changed, 794 insertions(+)
>>   create mode 100644 drivers/tty/serial/sprd_serial.c
>>
>> diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
>> index c79b43c..969d3cd 100644
>> --- a/drivers/tty/serial/Kconfig
>> +++ b/drivers/tty/serial/Kconfig
>> @@ -1577,6 +1577,24 @@ config SERIAL_MEN_Z135
>>   	  This driver can also be build as a module. If so, the module will be called
>>   	  men_z135_uart.ko
>>   
>> +config SERIAL_SPRD
>> +	tristate "Support for SPRD serial"
>> +	depends on ARCH_SPRD
>> +	select SERIAL_CORE
>> +	help
>> +	  This enables the driver for the Spreadtrum's serial.
>> +
>> +config SERIAL_SPRD_CONSOLE
>> +	bool "SPRD UART console support"
>> +	depends on SERIAL_SPRD=y
>> +	select SERIAL_CORE_CONSOLE
>> +	select SERIAL_EARLYCON
>> +	help
>> +	  Support for early debug console using Spreadtrum's serial. This enables
>> +	  the console before standard serial driver is probed. This is enabled
>> +	  with "earlycon" on the kernel command line. The console is
>> +	  enabled when early_param is processed.
>> +
>>   endmenu
>>   
>>   config SERIAL_MCTRL_GPIO
>> diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
>> index 9a548ac..4801aca 100644
>> --- a/drivers/tty/serial/Makefile
>> +++ b/drivers/tty/serial/Makefile
>> @@ -93,6 +93,7 @@ obj-$(CONFIG_SERIAL_ARC)	+= arc_uart.o
>>   obj-$(CONFIG_SERIAL_RP2)	+= rp2.o
>>   obj-$(CONFIG_SERIAL_FSL_LPUART)	+= fsl_lpuart.o
>>   obj-$(CONFIG_SERIAL_MEN_Z135)	+= men_z135_uart.o
>> +obj-$(CONFIG_SERIAL_SPRD) += sprd_serial.o
>>   
>>   # GPIOLIB helpers for modem control lines
>>   obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
>> diff --git a/drivers/tty/serial/sprd_serial.c b/drivers/tty/serial/sprd_serial.c
>> new file mode 100644
>> index 0000000..81839e4
>> --- /dev/null
>> +++ b/drivers/tty/serial/sprd_serial.c
>> @@ -0,0 +1,772 @@
>> +/*
>> + * Copyright (C) 2012 Spreadtrum Communications Inc.
>> + *
>> + * This software is licensed under the terms of the GNU General Public
>> + * License version 2, as published by the Free Software Foundation, and
>> + * may be copied, distributed, and modified under those terms.
>> + *
>> + * This program is distributed in the hope that it will be useful,
>> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
>> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
>> + * GNU General Public License for more details.
>> + */
>> +
>> +#include <linux/clk.h>
>> +#include <linux/console.h>
>> +#include <linux/delay.h>
>> +#include <linux/io.h>
>> +#include <linux/ioport.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of.h>
>> +#include <linux/platform_device.h>
>> +#include <linux/serial_core.h>
>> +#include <linux/serial.h>
>> +#include <linux/slab.h>
>> +#include <linux/tty.h>
>> +#include <linux/tty_flip.h>
>> +
>> +/* device name */
>> +#define UART_NR_MAX		8
>> +#define SPRD_TTY_NAME		"ttySPX"
>> +#define SPRD_FIFO_SIZE		128
>> +#define SPRD_DEF_RATE		26000000
>> +#define SPRD_TIMEOUT		2048
>> +
>> +/* the offset of serial registers and BITs for them */
>> +/* data registers */
>> +#define SPRD_TXD		0x0000
>> +#define SPRD_RXD		0x0004
>> +
>> +/* line status register and its BITs  */
>> +#define SPRD_LSR		0x0008
>> +#define SPRD_LSR_OE		BIT(4)
>> +#define SPRD_LSR_FE		BIT(3)
>> +#define SPRD_LSR_PE		BIT(2)
>> +#define SPRD_LSR_BI		BIT(7)
>> +#define SPRD_LSR_TX_OVER	BIT(15)
>> +
>> +/* data number in TX and RX fifo */
>> +#define SPRD_STS1		0x000C
>> +
>> +/* interrupt enable register and its BITs */
>> +#define SPRD_IEN		0x0010
>> +#define SPRD_IEN_RX_FULL	BIT(0)
>> +#define SPRD_IEN_TX_EMPTY	BIT(1)
>> +#define SPRD_IEN_BREAK_DETECT	BIT(7)
>> +#define SPRD_IEN_TIMEOUT	BIT(13)
>> +
>> +/* interrupt clear register */
>> +#define SPRD_ICLR		0x0014
>> +
>> +/* line control register */
>> +#define SPRD_LCR		0x0018
>> +#define SPRD_LCR_STOP_1BIT	0x10
>> +#define SPRD_LCR_STOP_2BIT	0x30
>> +#define SPRD_LCR_DATA_LEN	(BIT(2) | BIT(3))
>> +#define SPRD_LCR_DATA_LEN5	0x0
>> +#define SPRD_LCR_DATA_LEN6	0x4
>> +#define SPRD_LCR_DATA_LEN7	0x8
>> +#define SPRD_LCR_DATA_LEN8	0xc
>> +#define SPRD_LCR_PARITY		(BIT(0) | BIT(1))
>> +#define SPRD_LCR_PARITY_EN	0x2
>> +#define SPRD_LCR_EVEN_PAR	0x0
>> +#define SPRD_LCR_ODD_PAR	0x1
>> +
>> +/* control register 1 */
>> +#define SPRD_CTL1		0x001C
>> +#define RX_HW_FLOW_CTL_THLD	BIT(6)
>> +#define RX_HW_FLOW_CTL_EN	BIT(7)
>> +#define TX_HW_FLOW_CTL_EN	BIT(8)
>> +
>> +/* fifo threshold register */
>> +#define SPRD_CTL2		0x0020
>> +#define THLD_TX_EMPTY		0x40
>> +#define THLD_RX_FULL		0x40
>> +
>> +/* config baud rate register */
>> +#define SPRD_CLKD0		0x0024
>> +#define SPRD_CLKD1		0x0028
>> +
>> +/* interrupt mask status register */
>> +#define SPRD_IMSR		0x002C
>> +#define SPRD_IMSR_RX_FIFO_FULL	BIT(0)
>> +#define SPRD_IMSR_TX_FIFO_EMPTY	BIT(1)
>> +#define SPRD_IMSR_BREAK_DETECT	BIT(7)
>> +#define SPRD_IMSR_TIMEOUT	BIT(13)
>> +
>> +struct reg_backup {
>> +	uint32_t ien;
>> +	uint32_t ctrl0;
>> +	uint32_t ctrl1;
>> +	uint32_t ctrl2;
>> +	uint32_t clkd0;
>> +	uint32_t clkd1;
>> +	uint32_t dspwait;
>> +};
>> +
>> +struct sprd_uart_port {
>> +	struct uart_port port;
>> +	struct reg_backup reg_bak;
>> +	char name[16];
>> +};
>> +
>> +static struct sprd_uart_port *sprd_port[UART_NR_MAX] = { NULL };
>> +
>> +static inline unsigned int serial_in(struct uart_port *port, int offset)
>> +{
>> +	return readl_relaxed(port->membase + offset);
>> +}
>> +
>> +static inline void serial_out(struct uart_port *port, int offset, int value)
>> +{
>> +	writel_relaxed(value, port->membase + offset);
>> +}
>> +
>> +static unsigned int sprd_tx_empty(struct uart_port *port)
>> +{
>> +	if (serial_in(port, SPRD_STS1) & 0xff00)
>> +		return 0;
>> +	else
>> +		return TIOCSER_TEMT;
>> +}
>> +
>> +static unsigned int sprd_get_mctrl(struct uart_port *port)
>> +{
>> +	return TIOCM_DSR | TIOCM_CTS;
>> +}
>> +
>> +static void sprd_set_mctrl(struct uart_port *port, unsigned int mctrl)
>> +{
>> +	/* nothing to do */
>> +}
>> +
>> +static void sprd_stop_tx(struct uart_port *port)
>> +{
>> +	unsigned int ien, iclr;
>> +
>> +	iclr = serial_in(port, SPRD_ICLR);
>> +	ien = serial_in(port, SPRD_IEN);
>> +
>> +	iclr |= SPRD_IEN_TX_EMPTY;
>> +	ien &= ~SPRD_IEN_TX_EMPTY;
>> +
>> +	serial_out(port, SPRD_ICLR, iclr);
>> +	serial_out(port, SPRD_IEN, ien);
>> +}
>> +
>> +static void sprd_start_tx(struct uart_port *port)
>> +{
>> +	unsigned int ien;
>> +
>> +	ien = serial_in(port, SPRD_IEN);
>> +	if (!(ien & SPRD_IEN_TX_EMPTY)) {
>> +		ien |= SPRD_IEN_TX_EMPTY;
>> +		serial_out(port, SPRD_IEN, ien);
>> +	}
>> +}
>> +
>> +static void sprd_stop_rx(struct uart_port *port)
>> +{
>> +	unsigned int ien, iclr;
>> +
>> +	iclr = serial_in(port, SPRD_ICLR);
>> +	ien = serial_in(port, SPRD_IEN);
>> +
>> +	ien &= ~(SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT);
>> +	iclr |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT;
>> +
>> +	serial_out(port, SPRD_IEN, ien);
>> +	serial_out(port, SPRD_ICLR, iclr);
>> +}
>> +
>> +/* The Sprd serial does not support this function. */
>> +static void sprd_break_ctl(struct uart_port *port, int break_state)
>> +{
>> +	/* nothing to do */
>> +}
>> +
>> +static inline int handle_lsr_errors(struct uart_port *port,
>> +				    unsigned int *flag,
>> +				    unsigned int *lsr)
>> +{
>> +	int ret = 0;
>> +
>> +	/* statistics */
>> +	if (*lsr & SPRD_LSR_BI) {
>> +		*lsr &= ~(SPRD_LSR_FE | SPRD_LSR_PE);
>> +		port->icount.brk++;
>> +		ret = uart_handle_break(port);
>> +		if (ret)
>> +			return ret;
>> +	} else if (*lsr & SPRD_LSR_PE)
>> +		port->icount.parity++;
>> +	else if (*lsr & SPRD_LSR_FE)
>> +		port->icount.frame++;
>> +	if (*lsr & SPRD_LSR_OE)
>> +		port->icount.overrun++;
>> +
>> +	/* mask off conditions which should be ignored */
>> +	*lsr &= port->read_status_mask;
>> +	if (*lsr & SPRD_LSR_BI)
>> +		*flag = TTY_BREAK;
>> +	else if (*lsr & SPRD_LSR_PE)
>> +		*flag = TTY_PARITY;
>> +	else if (*lsr & SPRD_LSR_FE)
>> +		*flag = TTY_FRAME;
>> +
>> +	return ret;
>> +}
>> +
>> +static inline void sprd_rx(int irq, void *dev_id)
>> +{
>> +	struct uart_port *port = dev_id;
>> +	struct tty_port *tty = &port->state->port;
>> +	unsigned int ch, flag, lsr, max_count = SPRD_TIMEOUT;
>> +
>> +	while ((serial_in(port, SPRD_STS1) & 0x00ff) && max_count--) {
>> +		lsr = serial_in(port, SPRD_LSR);
>> +		ch = serial_in(port, SPRD_RXD);
>> +		flag = TTY_NORMAL;
>> +		port->icount.rx++;
>> +
>> +		if (lsr & (SPRD_LSR_BI | SPRD_LSR_PE
>> +			| SPRD_LSR_FE | SPRD_LSR_OE))
>> +			if (handle_lsr_errors(port, &lsr, &flag))
>> +				continue;
>> +		if (uart_handle_sysrq_char(port, ch))
>> +			continue;
>> +
>> +		uart_insert_char(port, lsr, SPRD_LSR_OE, ch, flag);
>> +	}
>> +
>> +	tty_flip_buffer_push(tty);
>> +}
>> +
>> +static inline void sprd_tx(int irq, void *dev_id)
>> +{
>> +	struct uart_port *port = dev_id;
>> +	struct circ_buf *xmit = &port->state->xmit;
>> +	int count;
>> +
>> +	if (port->x_char) {
>> +		serial_out(port, SPRD_TXD, port->x_char);
>> +		port->icount.tx++;
>> +		port->x_char = 0;
>> +		return;
>> +	}
>> +
>> +	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
>> +		sprd_stop_tx(port);
>> +		return;
>> +	}
>> +
>> +	count = THLD_TX_EMPTY;
>> +	do {
>> +		serial_out(port, SPRD_TXD, xmit->buf[xmit->tail]);
>> +		xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
>> +		port->icount.tx++;
>> +		if (uart_circ_empty(xmit))
>> +			break;
>> +	} while (--count > 0);
>> +
>> +	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
>> +		uart_write_wakeup(port);
>> +
>> +	if (uart_circ_empty(xmit))
>> +		sprd_stop_tx(port);
>> +}
>> +
>> +/* this handles the interrupt from one port */
>> +static irqreturn_t sprd_handle_irq(int irq, void *dev_id)
>> +{
>> +	struct uart_port *port = (struct uart_port *)dev_id;
>> +	unsigned int ims;
> Why does your isr not have to take port->lock ?

The original consideration is the registers are accessed by isr only.
Interrupt will not be nested because of gic chip driver protection.
So there is not other thread will race on it.
Does this make sense?

>
>> +	ims = serial_in(port, SPRD_IMSR);
>> +
>> +	if (!ims)
>> +		return IRQ_NONE;
>> +
>> +	serial_out(port, SPRD_ICLR, ~0);
>> +
>> +	if (ims & (SPRD_IMSR_RX_FIFO_FULL |
>> +		SPRD_IMSR_BREAK_DETECT | SPRD_IMSR_TIMEOUT))
>> +		sprd_rx(irq, port);
>> +
>> +	if (ims & SPRD_IMSR_TX_FIFO_EMPTY)
>> +		sprd_tx(irq, port);
>> +
>> +	return IRQ_HANDLED;
>> +}
>> +
>> +static int sprd_startup(struct uart_port *port)
>> +{
>> +	int ret = 0;
>> +	unsigned int ien, ctrl1;
>> +	unsigned int timeout;
>> +	struct sprd_uart_port *sp;
>> +
>> +	serial_out(port, SPRD_CTL2, ((THLD_TX_EMPTY << 8) | THLD_RX_FULL));
>> +
>> +	/* clear rx fifo */
>> +	timeout = SPRD_TIMEOUT;
>> +	while (timeout-- && serial_in(port, SPRD_STS1) & 0x00ff)
>> +		serial_in(port, SPRD_RXD);
>> +
>> +	/* clear tx fifo */
>> +	timeout = SPRD_TIMEOUT;
>> +	while (timeout-- && serial_in(port, SPRD_STS1) & 0xff00)
>> +		cpu_relax();
>> +
>> +	/* clear interrupt */
>> +	serial_out(port, SPRD_IEN, 0x0);
>> +	serial_out(port, SPRD_ICLR, ~0);
>> +
>> +	/* allocate irq */
>> +	sp = container_of(port, struct sprd_uart_port, port);
>> +	snprintf(sp->name, sizeof(sp->name), "sprd_serial%d", port->line);
>> +	ret = devm_request_irq(port->dev, port->irq, sprd_handle_irq,
>> +				IRQF_SHARED, sp->name, port);
>> +	if (ret) {
>> +		dev_err(port->dev, "fail to request serial irq %d, ret=%d\n",
>> +			port->irq, ret);
>> +		return ret;
>> +	}
>> +	ctrl1 = serial_in(port, SPRD_CTL1);
>> +	ctrl1 |= 0x3e00 | THLD_RX_FULL;
>> +	serial_out(port, SPRD_CTL1, ctrl1);
>> +
>> +	/* enable interrupt */
>> +	spin_lock(&port->lock);
>> +	ien = serial_in(port, SPRD_IEN);
>> +	ien |= SPRD_IEN_RX_FULL | SPRD_IEN_BREAK_DETECT | SPRD_IEN_TIMEOUT;
>> +	serial_out(port, SPRD_IEN, ien);
>> +	spin_unlock(&port->lock);
>> +
>> +	return 0;
>> +}
>> +
>> +static void sprd_shutdown(struct uart_port *port)
>> +{
>> +	serial_out(port, SPRD_IEN, 0x0);
>> +	serial_out(port, SPRD_ICLR, ~0);
>> +	devm_free_irq(port->dev, port->irq, port);
>> +}
>> +
>> +static void sprd_set_termios(struct uart_port *port,
>> +				    struct ktermios *termios,
>> +				    struct ktermios *old)
>> +{
>> +	unsigned int baud, quot;
>> +	unsigned int lcr, fc;
>> +
>> +	/* ask the core to calculate the divisor for us */
>> +	baud = uart_get_baud_rate(port, termios, old, 1200, 3000000);
>> +
>> +	quot = (unsigned int)((port->uartclk + baud / 2) / baud);
>> +
>> +	/* set data length */
>> +	lcr = serial_in(port, SPRD_LCR);
>> +	lcr &= ~SPRD_LCR_DATA_LEN;
>> +	switch (termios->c_cflag & CSIZE) {
>> +	case CS5:
>> +		lcr |= SPRD_LCR_DATA_LEN5;
>> +		break;
>> +	case CS6:
>> +		lcr |= SPRD_LCR_DATA_LEN6;
>> +		break;
>> +	case CS7:
>> +		lcr |= SPRD_LCR_DATA_LEN7;
>> +		break;
>> +	case CS8:
>> +	default:
>> +		lcr |= SPRD_LCR_DATA_LEN8;
>> +		break;
>> +	}
>> +
>> +	/* calculate stop bits */
>> +	lcr &= ~(SPRD_LCR_STOP_1BIT | SPRD_LCR_STOP_2BIT);
>> +	if (termios->c_cflag & CSTOPB)
>> +		lcr |= SPRD_LCR_STOP_2BIT;
>> +	else
>> +		lcr |= SPRD_LCR_STOP_1BIT;
>> +
>> +	/* calculate parity */
>> +	lcr &= ~SPRD_LCR_PARITY;
>> +	termios->c_cflag &= ~CMSPAR;	/* no support mark/space */
>> +	if (termios->c_cflag & PARENB) {
>> +		lcr |= SPRD_LCR_PARITY_EN;
>> +		if (termios->c_cflag & PARODD)
>> +			lcr |= SPRD_LCR_ODD_PAR;
>> +		else
>> +			lcr |= SPRD_LCR_EVEN_PAR;
>> +	}
>> +
>> +	/* change the port state. */
>             ^^^^^^^^^^^^^^^^^^^^^^
>
> This means you should be taking the port->lock here... (and disabling
> local interrupts if your isr takes the port->lock)

Yes, I think you are right.


>
>> +	/* update the per-port timeout */
>> +	uart_update_timeout(port, termios->c_cflag, baud);
>> +
>> +	port->read_status_mask = SPRD_LSR_OE;
>> +	if (termios->c_iflag & INPCK)
>> +		port->read_status_mask |= SPRD_LSR_FE | SPRD_LSR_PE;
>> +	if (termios->c_iflag & (BRKINT | PARMRK))
>> +		port->read_status_mask |= SPRD_LSR_BI;
>> +
>> +	/* characters to ignore */
>> +	port->ignore_status_mask = 0;
>> +	if (termios->c_iflag & IGNPAR)
>> +		port->ignore_status_mask |= SPRD_LSR_PE | SPRD_LSR_FE;
>> +	if (termios->c_iflag & IGNBRK) {
>> +		port->ignore_status_mask |= SPRD_LSR_BI;
>> +		/*
>> +		 * If we're ignoring parity and break indicators,
>> +		 * ignore overruns too (for real raw support).
>> +		 */
>> +		if (termios->c_iflag & IGNPAR)
>> +			port->ignore_status_mask |= SPRD_LSR_OE;
>> +	}
>> +
>> +	/* flow control */
>> +	fc = serial_in(port, SPRD_CTL1);
>> +	fc &= ~(RX_HW_FLOW_CTL_THLD | RX_HW_FLOW_CTL_EN | TX_HW_FLOW_CTL_EN);
>> +	if (termios->c_cflag & CRTSCTS) {
>> +		fc |= RX_HW_FLOW_CTL_THLD;
>> +		fc |= RX_HW_FLOW_CTL_EN;
>> +		fc |= TX_HW_FLOW_CTL_EN;
>> +	}
>> +
>> +	/* clock divider bit0~bit15 */
>> +	serial_out(port, SPRD_CLKD0, quot & 0xffff);
>> +
>> +	/* clock divider bit16~bit20 */
>> +	serial_out(port, SPRD_CLKD1, (quot & 0x1f0000) >> 16);
>> +	serial_out(port, SPRD_LCR, lcr);
>> +	fc |= 0x3e00 | THLD_RX_FULL;
>> +	serial_out(port, SPRD_CTL1, fc);
> and dropping it here.
>
>> +	/* Don't rewrite B0 */
>> +	if (tty_termios_baud_rate(termios))
>> +		tty_termios_encode_baud_rate(termios, baud, baud);
>> +}
>> +
>> +static const char *sprd_type(struct uart_port *port)
>> +{
>> +	return "SPX";
>> +}
>> +
>> +static void sprd_release_port(struct uart_port *port)
>> +{
>> +	/* nothing to do */
>> +}
>> +
>> +static int sprd_request_port(struct uart_port *port)
>> +{
>> +	return 0;
>> +}
>> +
>> +static void sprd_config_port(struct uart_port *port, int flags)
>> +{
>> +	if (flags & UART_CONFIG_TYPE)
>> +		port->type = PORT_SPRD;
>> +}
>> +
>> +static int sprd_verify_port(struct uart_port *port,
>> +				   struct serial_struct *ser)
>> +{
>> +	if (ser->type != PORT_SPRD)
>> +		return -EINVAL;
>> +	if (port->irq != ser->irq)
>> +		return -EINVAL;
>> +	return 0;
>> +}
>> +
>> +static struct uart_ops serial_sprd_ops = {
>> +	.tx_empty = sprd_tx_empty,
>> +	.get_mctrl = sprd_get_mctrl,
>> +	.set_mctrl = sprd_set_mctrl,
>> +	.stop_tx = sprd_stop_tx,
>> +	.start_tx = sprd_start_tx,
>> +	.stop_rx = sprd_stop_rx,
>> +	.break_ctl = sprd_break_ctl,
>> +	.startup = sprd_startup,
>> +	.shutdown = sprd_shutdown,
>> +	.set_termios = sprd_set_termios,
>> +	.type = sprd_type,
>> +	.release_port = sprd_release_port,
>> +	.request_port = sprd_request_port,
>> +	.config_port = sprd_config_port,
>> +	.verify_port = sprd_verify_port,
>> +};
>> +
>> +#ifdef CONFIG_SERIAL_SPRD_CONSOLE
>> +static inline void wait_for_xmitr(struct uart_port *port)
>> +{
>> +	unsigned int status, tmout = 10000;
>> +
>> +	/* wait up to 10ms for the character(s) to be sent */
>> +	do {
>> +		status = serial_in(port, SPRD_STS1);
>> +		if (--tmout == 0)
>> +			break;
>> +		udelay(1);
>> +	} while (status & 0xff00);
>> +}
>> +
>> +static void sprd_console_putchar(struct uart_port *port, int ch)
>> +{
>> +	wait_for_xmitr(port);
>> +	serial_out(port, SPRD_TXD, ch);
>> +}
>> +
>> +static void sprd_console_write(struct console *co, const char *s,
>> +				      unsigned int count)
>> +{
>> +	struct uart_port *port = &sprd_port[co->index]->port;
>> +	int ien;
>> +	int locked = 1;
>> +
>> +	if (oops_in_progress)
>> +		locked = spin_trylock(&port->lock);
>> +	else
>> +		spin_lock(&port->lock);
> If you do need to take the port->lock in your isr, then you need to
> disable local irq here.

You mean to use spin_lock_irqsave()?

We do disable irq below....

>
>> +	/* save the IEN then disable the interrupts */
>> +	ien = serial_in(port, SPRD_IEN);
>> +	serial_out(port, SPRD_IEN, 0x0);

Here, we disable port IEN register.

>> +
>> +	uart_console_write(port, s, count, sprd_console_putchar);
>> +
>> +	/* wait for transmitter to become empty and restore the IEN */
>> +	wait_for_xmitr(port);
>> +	serial_out(port, SPRD_IEN, ien);
>> +	if (locked)
>> +		spin_unlock(&port->lock);
>> +}
>> +
>> +static int __init sprd_console_setup(struct console *co, char *options)
>> +{
>> +	struct uart_port *port;
>> +	int baud = 115200;
>> +	int bits = 8;
>> +	int parity = 'n';
>> +	int flow = 'n';
>> +
>> +	if (co->index >= UART_NR_MAX || co->index < 0)
>> +		co->index = 0;
>> +
>> +	port = &sprd_port[co->index]->port;
>> +	if (port == NULL) {
>> +		pr_info("serial port %d not yet initialized\n", co->index);
>> +		return -ENODEV;
>> +	}
>> +	if (options)
>> +		uart_parse_options(options, &baud, &parity, &bits, &flow);
>> +
>> +	return uart_set_options(port, co, baud, parity, bits, flow);
>> +}
>> +
>> +static struct uart_driver sprd_uart_driver;
>> +static struct console sprd_console = {
>> +	.name = SPRD_TTY_NAME,
>> +	.write = sprd_console_write,
>> +	.device = uart_console_device,
>> +	.setup = sprd_console_setup,
>> +	.flags = CON_PRINTBUFFER,
>> +	.index = -1,
>> +	.data = &sprd_uart_driver,
>> +};
>> +
>> +#define SPRD_CONSOLE	(&sprd_console)
>> +
>> +/* Support for earlycon */
>> +static void sprd_putc(struct uart_port *port, int c)
>> +{
>> +	unsigned int timeout = SPRD_TIMEOUT;
>> +
>> +	while (timeout-- &&
>> +		   !(readl(port->membase + SPRD_LSR) & SPRD_LSR_TX_OVER))
>> +		cpu_relax();
>> +
>> +	writeb(c, port->membase + SPRD_TXD);
>> +}
>> +
>> +static void sprd_early_write(struct console *con, const char *s,
>> +				    unsigned n)
>> +{
>> +	struct earlycon_device *dev = con->data;
>> +
>> +	uart_console_write(&dev->port, s, n, sprd_putc);
>> +}
>> +
>> +static int __init sprd_early_console_setup(
>> +				struct earlycon_device *device,
>> +				const char *opt)
>> +{
>> +	if (!device->port.membase)
>> +		return -ENODEV;
>> +
>> +	device->con->write = sprd_early_write;
>> +	return 0;
>> +}
>> +
>> +EARLYCON_DECLARE(sprd_serial, sprd_early_console_setup);
>> +OF_EARLYCON_DECLARE(sprd_serial, "sprd,sc9836-uart",
>> +		    sprd_early_console_setup);
>> +
>> +#else /* !CONFIG_SERIAL_SPRD_CONSOLE */
>> +#define SPRD_CONSOLE		NULL
>> +#endif
>> +
>> +static struct uart_driver sprd_uart_driver = {
>> +	.owner = THIS_MODULE,
>> +	.driver_name = "sprd_serial",
>> +	.dev_name = SPRD_TTY_NAME,
>> +	.major = 0,
>> +	.minor = 0,
>> +	.nr = UART_NR_MAX,
>> +	.cons = SPRD_CONSOLE,
>> +};
>> +
>> +static int sprd_probe(struct platform_device *pdev)
>> +{
>> +	struct resource *res;
>> +	struct device_node *np = pdev->dev.of_node;
>> +	struct uart_port *up;
>> +	struct clk *clk;
>> +	int irq;
>> +
>> +	if (np)
>> +		pdev->id = of_alias_get_id(np, "serial");
>> +
>> +	if (pdev->id < 0 || pdev->id >= UART_NR_MAX) {
>> +		dev_err(&pdev->dev, "does not support id %d\n", pdev->id);
>> +		return -ENXIO;
>> +	}
>> +
>> +	sprd_port[pdev->id] = devm_kzalloc(&pdev->dev,
>> +		sizeof(*sprd_port[pdev->id]), GFP_KERNEL);
>> +	if (!sprd_port[pdev->id])
>> +		return -ENOMEM;
>> +
>> +	up = &sprd_port[pdev->id]->port;
>> +	up->dev = &pdev->dev;
>> +	up->line = pdev->id;
>> +	up->type = PORT_SPRD;
>> +	up->iotype = SERIAL_IO_PORT;
>> +	up->uartclk = SPRD_DEF_RATE;
>> +	up->fifosize = SPRD_FIFO_SIZE;
>> +	up->ops = &serial_sprd_ops;
>> +	up->flags = ASYNC_BOOT_AUTOCONF;
>> +
>> +	clk = devm_clk_get(&pdev->dev, NULL);
>> +	if (!IS_ERR(clk))
>> +		up->uartclk = clk_get_rate(clk);
>> +
>> +	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> +	if (!res) {
>> +		dev_err(&pdev->dev, "not provide mem resource\n");
>> +		return -ENODEV;
>> +	}
>> +	up->mapbase = res->start;
>> +	up->membase = devm_ioremap_resource(&pdev->dev, res);
>> +	if (IS_ERR(up->membase))
>> +		return PTR_ERR(up->membase);
>> +
>> +	irq = platform_get_irq(pdev, 0);
>> +	if (irq < 0) {
>> +		dev_err(&pdev->dev, "not provide irq resource\n");
>> +		return -ENODEV;
>> +	}
>> +	up->irq = irq;
>> +
>> +	platform_set_drvdata(pdev, up);
>> +
>> +	return uart_add_one_port(&sprd_uart_driver, up);
>> +}
>> +
>> +static int sprd_remove(struct platform_device *dev)
>> +{
>> +	struct uart_port *up = platform_get_drvdata(dev);
>> +
>> +	return uart_remove_one_port(&sprd_uart_driver, up);
>> +}
>> +
>> +static int sprd_suspend(struct device *dev)
>> +{
>> +	int id = to_platform_device(dev)->id;
>> +	struct uart_port *port = &sprd_port[id]->port;
>> +	struct reg_backup *reg_bak = &sprd_port[id]->reg_bak;
>> +
>> +	reg_bak->ien = serial_in(port, SPRD_IEN);
>> +	reg_bak->ctrl0 = serial_in(port, SPRD_LCR);
>> +	reg_bak->ctrl1 = serial_in(port, SPRD_CTL1);
>> +	reg_bak->ctrl2 = serial_in(port, SPRD_CTL2);
>> +	reg_bak->clkd0 = serial_in(port, SPRD_CLKD0);
>> +	reg_bak->clkd1 = serial_in(port, SPRD_CLKD1);
> Why are you saving and restoring these register states
> across suspend/resume?
>
> The serial core calls your set_termios() handler upon
> resume (either for the console or if a tty is open)
> so you should be reprogramming the hardware there
> based on the termios settings.

We'll try to address it in V6.

Thanks,
Orson


>
> Regards,
> Peter Hurley
>> +
>> +	uart_suspend_port(&sprd_uart_driver, port);
>> +
>> +	return 0;
>> +}
>> +
>> +static int sprd_resume(struct device *dev)
>> +{
>> +	int id = to_platform_device(dev)->id;
>> +	struct uart_port *port = &sprd_port[id]->port;
>> +	struct reg_backup *reg_bak = &sprd_port[id]->reg_bak;
>> +
>> +	serial_out(port, SPRD_LCR, reg_bak->ctrl0);
>> +	serial_out(port, SPRD_CTL1, reg_bak->ctrl1);
>> +	serial_out(port, SPRD_CTL2, reg_bak->ctrl2);
>> +	serial_out(port, SPRD_CLKD0, reg_bak->clkd0);
>> +	serial_out(port, SPRD_CLKD1, reg_bak->clkd1);
>> +	serial_out(port, SPRD_IEN, reg_bak->ien);
>> +
>> +	uart_resume_port(&sprd_uart_driver, port);
>> +
>> +	return 0;
>> +}
>> +
>> +static const struct of_device_id serial_ids[] = {
>> +	{.compatible = "sprd,sc9836-uart",},
>> +	{}
>> +};
>> +
>> +static SIMPLE_DEV_PM_OPS(sprd_pm_ops, sprd_suspend, sprd_resume);
>> +
>> +static struct platform_driver sprd_platform_driver = {
>> +	.probe		= sprd_probe,
>> +	.remove		= sprd_remove,
>> +	.driver 	= {
>> +		.name	= "sprd_serial",
>> +		.of_match_table = of_match_ptr(serial_ids),
>> +		.pm	= &sprd_pm_ops,
>> +	},
>> +};
>> +
>> +static int __init sprd_serial_init(void)
>> +{
>> +	int ret = 0;
>> +
>> +	ret = uart_register_driver(&sprd_uart_driver);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = platform_driver_register(&sprd_platform_driver);
>> +	if (ret)
>> +		uart_unregister_driver(&sprd_uart_driver);
>> +
>> +	return ret;
>> +}
>> +
>> +static void __exit sprd_serial_exit(void)
>> +{
>> +	platform_driver_unregister(&sprd_platform_driver);
>> +	uart_unregister_driver(&sprd_uart_driver);
>> +}
>> +
>> +module_init(sprd_serial_init);
>> +module_exit(sprd_serial_exit);
>> +
>> +MODULE_LICENSE("GPL v2");
>> +MODULE_DESCRIPTION("Spreadtrum SoC serial driver series");
>> diff --git a/include/uapi/linux/serial_core.h b/include/uapi/linux/serial_core.h
>> index c172180..7e6eb39 100644
>> --- a/include/uapi/linux/serial_core.h
>> +++ b/include/uapi/linux/serial_core.h
>> @@ -248,4 +248,7 @@
>>   /* MESON */
>>   #define PORT_MESON	109
>>   
>> +/* SPRD SERIAL  */
>> +#define PORT_SPRD	110
>> +
>>   #endif /* _UAPILINUX_SERIAL_CORE_H */
>>

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