msm_serial: Add support for poll_{get,put}_char()

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>

1 files changed, 137 insertions, 3 deletions

diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index b5d779cd3c2b..053b98eb46c8 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -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];
@@ -309,6 +316,8 @@ 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);
@@ -316,6 +325,10 @@ static void msm_reset(struct uart_port *port)
         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)
@@ -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,
@@ -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[] = {
@@ -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 },
         { }
 };
 
@@ -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)
@@ -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;