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msm_serial: Add support for poll_{get,put}_char()
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Implement the polling functionality for the MSM serial driver.
This allows us to use KGDB on this hardware.

Cc: David Brown <davidb@codeaurora.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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Stephen Boyd authored and Greg Kroah-Hartman committed Feb 12, 2014
1 parent b28a960 commit f7e54d7
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Showing 2 changed files with 146 additions and 3 deletions.
140 changes: 137 additions & 3 deletions drivers/tty/serial/msm_serial.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,13 @@

#include "msm_serial.h"

enum {
UARTDM_1P1 = 1,
UARTDM_1P2,
UARTDM_1P3,
UARTDM_1P4,
};

struct msm_port {
struct uart_port uart;
char name[16];
Expand Down Expand Up @@ -309,13 +316,19 @@ static unsigned int msm_get_mctrl(struct uart_port *port)

static void msm_reset(struct uart_port *port)
{
struct msm_port *msm_port = UART_TO_MSM(port);

/* reset everything */
msm_write(port, UART_CR_CMD_RESET_RX, UART_CR);
msm_write(port, UART_CR_CMD_RESET_TX, UART_CR);
msm_write(port, UART_CR_CMD_RESET_ERR, UART_CR);
msm_write(port, UART_CR_CMD_RESET_BREAK_INT, UART_CR);
msm_write(port, UART_CR_CMD_RESET_CTS, UART_CR);
msm_write(port, UART_CR_CMD_SET_RFR, UART_CR);

/* Disable DM modes */
if (msm_port->is_uartdm)
msm_write(port, 0, UARTDM_DMEN);
}

static void msm_set_mctrl(struct uart_port *port, unsigned int mctrl)
Expand Down Expand Up @@ -711,6 +724,117 @@ static void msm_power(struct uart_port *port, unsigned int state,
}
}

#ifdef CONFIG_CONSOLE_POLL
static int msm_poll_init(struct uart_port *port)
{
struct msm_port *msm_port = UART_TO_MSM(port);

/* Enable single character mode on RX FIFO */
if (msm_port->is_uartdm >= UARTDM_1P4)
msm_write(port, UARTDM_DMEN_RX_SC_ENABLE, UARTDM_DMEN);

return 0;
}

static int msm_poll_get_char_single(struct uart_port *port)
{
struct msm_port *msm_port = UART_TO_MSM(port);
unsigned int rf_reg = msm_port->is_uartdm ? UARTDM_RF : UART_RF;

if (!(msm_read(port, UART_SR) & UART_SR_RX_READY))
return NO_POLL_CHAR;
else
return msm_read(port, rf_reg) & 0xff;
}

static int msm_poll_get_char_dm_1p3(struct uart_port *port)
{
int c;
static u32 slop;
static int count;
unsigned char *sp = (unsigned char *)&slop;

/* Check if a previous read had more than one char */
if (count) {
c = sp[sizeof(slop) - count];
count--;
/* Or if FIFO is empty */
} else if (!(msm_read(port, UART_SR) & UART_SR_RX_READY)) {
/*
* If RX packing buffer has less than a word, force stale to
* push contents into RX FIFO
*/
count = msm_read(port, UARTDM_RXFS);
count = (count >> UARTDM_RXFS_BUF_SHIFT) & UARTDM_RXFS_BUF_MASK;
if (count) {
msm_write(port, UART_CR_CMD_FORCE_STALE, UART_CR);
slop = msm_read(port, UARTDM_RF);
c = sp[0];
count--;
} else {
c = NO_POLL_CHAR;
}
/* FIFO has a word */
} else {
slop = msm_read(port, UARTDM_RF);
c = sp[0];
count = sizeof(slop) - 1;
}

return c;
}

static int msm_poll_get_char(struct uart_port *port)
{
u32 imr;
int c;
struct msm_port *msm_port = UART_TO_MSM(port);

/* Disable all interrupts */
imr = msm_read(port, UART_IMR);
msm_write(port, 0, UART_IMR);

if (msm_port->is_uartdm == UARTDM_1P3)
c = msm_poll_get_char_dm_1p3(port);
else
c = msm_poll_get_char_single(port);

/* Enable interrupts */
msm_write(port, imr, UART_IMR);

return c;
}

static void msm_poll_put_char(struct uart_port *port, unsigned char c)
{
u32 imr;
struct msm_port *msm_port = UART_TO_MSM(port);

/* Disable all interrupts */
imr = msm_read(port, UART_IMR);
msm_write(port, 0, UART_IMR);

if (msm_port->is_uartdm)
reset_dm_count(port, 1);

/* Wait until FIFO is empty */
while (!(msm_read(port, UART_SR) & UART_SR_TX_READY))
cpu_relax();

/* Write a character */
msm_write(port, c, msm_port->is_uartdm ? UARTDM_TF : UART_TF);

/* Wait until FIFO is empty */
while (!(msm_read(port, UART_SR) & UART_SR_TX_READY))
cpu_relax();

/* Enable interrupts */
msm_write(port, imr, UART_IMR);

return;
}
#endif

static struct uart_ops msm_uart_pops = {
.tx_empty = msm_tx_empty,
.set_mctrl = msm_set_mctrl,
Expand All @@ -729,6 +853,11 @@ static struct uart_ops msm_uart_pops = {
.config_port = msm_config_port,
.verify_port = msm_verify_port,
.pm = msm_power,
#ifdef CONFIG_CONSOLE_POLL
.poll_init = msm_poll_init,
.poll_get_char = msm_poll_get_char,
.poll_put_char = msm_poll_put_char,
#endif
};

static struct msm_port msm_uart_ports[] = {
Expand Down Expand Up @@ -900,7 +1029,10 @@ static struct uart_driver msm_uart_driver = {
static atomic_t msm_uart_next_id = ATOMIC_INIT(0);

static const struct of_device_id msm_uartdm_table[] = {
{ .compatible = "qcom,msm-uartdm" },
{ .compatible = "qcom,msm-uartdm-v1.1", .data = (void *)UARTDM_1P1 },
{ .compatible = "qcom,msm-uartdm-v1.2", .data = (void *)UARTDM_1P2 },
{ .compatible = "qcom,msm-uartdm-v1.3", .data = (void *)UARTDM_1P3 },
{ .compatible = "qcom,msm-uartdm-v1.4", .data = (void *)UARTDM_1P4 },
{ }
};

Expand All @@ -909,6 +1041,7 @@ static int __init msm_serial_probe(struct platform_device *pdev)
struct msm_port *msm_port;
struct resource *resource;
struct uart_port *port;
const struct of_device_id *id;
int irq;

if (pdev->id == -1)
Expand All @@ -923,8 +1056,9 @@ static int __init msm_serial_probe(struct platform_device *pdev)
port->dev = &pdev->dev;
msm_port = UART_TO_MSM(port);

if (of_match_device(msm_uartdm_table, &pdev->dev))
msm_port->is_uartdm = 1;
id = of_match_device(msm_uartdm_table, &pdev->dev);
if (id)
msm_port->is_uartdm = (unsigned long)id->data;
else
msm_port->is_uartdm = 0;

Expand Down
9 changes: 9 additions & 0 deletions drivers/tty/serial/msm_serial.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -59,6 +59,7 @@
#define UART_CR_CMD_RESET_RFR (14 << 4)
#define UART_CR_CMD_PROTECTION_EN (16 << 4)
#define UART_CR_CMD_STALE_EVENT_ENABLE (80 << 4)
#define UART_CR_CMD_FORCE_STALE (4 << 8)
#define UART_CR_CMD_RESET_TX_READY (3 << 8)
#define UART_CR_TX_DISABLE (1 << 3)
#define UART_CR_TX_ENABLE (1 << 2)
Expand Down Expand Up @@ -113,6 +114,14 @@
#define GSBI_PROTOCOL_UART 0x40
#define GSBI_PROTOCOL_IDLE 0x0

#define UARTDM_RXFS 0x50
#define UARTDM_RXFS_BUF_SHIFT 0x7
#define UARTDM_RXFS_BUF_MASK 0x7

#define UARTDM_DMEN 0x3C
#define UARTDM_DMEN_RX_SC_ENABLE BIT(5)
#define UARTDM_DMEN_TX_SC_ENABLE BIT(4)

#define UARTDM_DMRX 0x34
#define UARTDM_NCF_TX 0x40
#define UARTDM_RX_TOTAL_SNAP 0x38
Expand Down

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