serial: msm: Add support for UARTDM cores

Add support for the next-generation version of the MSM UART
to the msm_serial driver. This version of the hardware is
similar to the original version, but has some DMA
capabilities that are used in PIO mode in this driver.

Signed-off-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: David Brown <davidb@codeaurora.org>

2 files changed, 269 insertions, 45 deletions

diff --git a/drivers/serial/msm_serial.c b/drivers/serial/msm_serial.c
index 8e43a7b69e64..bfee9b4c6661 100644
--- a/drivers/serial/msm_serial.c
+++ b/drivers/serial/msm_serial.c
@@ -3,6 +3,7 @@
  *
  * Copyright (C) 2007 Google, Inc.
  * Author: Robert Love <rlove@google.com>
+ * Copyright (c) 2011, Code Aurora Forum. All rights reserved.
  *
  * This software is licensed under the terms of the GNU General Public
  * License version 2, as published by the Free Software Foundation, and
@@ -31,6 +32,7 @@
 #include <linux/serial.h>
 #include <linux/clk.h>
 #include <linux/platform_device.h>
+#include <linux/delay.h>
 
 #include "msm_serial.h"
 
@@ -38,9 +40,20 @@ struct msm_port {
         struct uart_port        uart;
         char                    name[16];
         struct clk              *clk;
+        struct clk              *pclk;
         unsigned int            imr;
+        unsigned int            *gsbi_base;
+        int                     is_uartdm;
+        unsigned int            old_snap_state;
 };
 
+static inline void wait_for_xmitr(struct uart_port *port, int bits)
+{
+        if (!(msm_read(port, UART_SR) & UART_SR_TX_EMPTY))
+                while ((msm_read(port, UART_ISR) & bits) != bits)
+                        cpu_relax();
+}
+
 static void msm_stop_tx(struct uart_port *port)
 {
         struct msm_port *msm_port = UART_TO_MSM(port);
@@ -73,6 +86,61 @@ static void msm_enable_ms(struct uart_port *port)
         msm_write(port, msm_port->imr, UART_IMR);
 }
 
+static void handle_rx_dm(struct uart_port *port, unsigned int misr)
+{
+        struct tty_struct *tty = port->state->port.tty;
+        unsigned int sr;
+        int count = 0;
+        struct msm_port *msm_port = UART_TO_MSM(port);
+
+        if ((msm_read(port, UART_SR) & UART_SR_OVERRUN)) {
+                port->icount.overrun++;
+                tty_insert_flip_char(tty, 0, TTY_OVERRUN);
+                msm_write(port, UART_CR_CMD_RESET_ERR, UART_CR);
+        }
+
+        if (misr & UART_IMR_RXSTALE) {
+                count = msm_read(port, UARTDM_RX_TOTAL_SNAP) -
+                        msm_port->old_snap_state;
+                msm_port->old_snap_state = 0;
+        } else {
+                count = 4 * (msm_read(port, UART_RFWR));
+                msm_port->old_snap_state += count;
+        }
+
+        /* TODO: Precise error reporting */
+
+        port->icount.rx += count;
+
+        while (count > 0) {
+                unsigned int c;
+
+                sr = msm_read(port, UART_SR);
+                if ((sr & UART_SR_RX_READY) == 0) {
+                        msm_port->old_snap_state -= count;
+                        break;
+                }
+                c = msm_read(port, UARTDM_RF);
+                if (sr & UART_SR_RX_BREAK) {
+                        port->icount.brk++;
+                        if (uart_handle_break(port))
+                                continue;
+                } else if (sr & UART_SR_PAR_FRAME_ERR)
+                        port->icount.frame++;
+
+                /* TODO: handle sysrq */
+                tty_insert_flip_string(tty, (char *) &c,
+                                       (count > 4) ? 4 : count);
+                count -= 4;
+        }
+
+        tty_flip_buffer_push(tty);
+        if (misr & (UART_IMR_RXSTALE))
+                msm_write(port, UART_CR_CMD_RESET_STALE_INT, UART_CR);
+        msm_write(port, 0xFFFFFF, UARTDM_DMRX);
+        msm_write(port, UART_CR_CMD_STALE_EVENT_ENABLE, UART_CR);
+}
+
 static void handle_rx(struct uart_port *port)
 {
         struct tty_struct *tty = port->state->port.tty;
@@ -121,6 +189,12 @@ static void handle_rx(struct uart_port *port)
         tty_flip_buffer_push(tty);
 }
 
+static void reset_dm_count(struct uart_port *port)
+{
+        wait_for_xmitr(port, UART_ISR_TX_READY);
+        msm_write(port, 1, UARTDM_NCF_TX);
+}
+
 static void handle_tx(struct uart_port *port)
 {
         struct circ_buf *xmit = &port->state->xmit;
@@ -128,11 +202,18 @@ static void handle_tx(struct uart_port *port)
         int sent_tx;
 
         if (port->x_char) {
-                msm_write(port, port->x_char, UART_TF);
+                if (msm_port->is_uartdm)
+                        reset_dm_count(port);
+
+                msm_write(port, port->x_char,
+                          msm_port->is_uartdm ? UARTDM_TF : UART_TF);
                 port->icount.tx++;
                 port->x_char = 0;
         }
 
+        if (msm_port->is_uartdm)
+                reset_dm_count(port);
+
         while (msm_read(port, UART_SR) & UART_SR_TX_READY) {
                 if (uart_circ_empty(xmit)) {
                         /* disable tx interrupts */
@@ -140,8 +221,11 @@ static void handle_tx(struct uart_port *port)
                         msm_write(port, msm_port->imr, UART_IMR);
                         break;
                 }
+                msm_write(port, xmit->buf[xmit->tail],
+                          msm_port->is_uartdm ? UARTDM_TF : UART_TF);
 
-                msm_write(port, xmit->buf[xmit->tail], UART_TF);
+                if (msm_port->is_uartdm)
+                        reset_dm_count(port);
 
                 xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                 port->icount.tx++;
@@ -169,8 +253,12 @@ static irqreturn_t msm_irq(int irq, void *dev_id)
         misr = msm_read(port, UART_MISR);
         msm_write(port, 0, UART_IMR); /* disable interrupt */
 
-        if (misr & (UART_IMR_RXLEV | UART_IMR_RXSTALE))
-                handle_rx(port);
+        if (misr & (UART_IMR_RXLEV | UART_IMR_RXSTALE)) {
+                if (msm_port->is_uartdm)
+                        handle_rx_dm(port, misr);
+                else
+                        handle_rx(port);
+        }
         if (misr & UART_IMR_TXLEV)
                 handle_tx(port);
         if (misr & UART_IMR_DELTA_CTS)
@@ -192,10 +280,21 @@ static unsigned int msm_get_mctrl(struct uart_port *port)
         return TIOCM_CAR | TIOCM_CTS | TIOCM_DSR | TIOCM_RTS;
 }
 
-static void msm_set_mctrl(struct uart_port *port, unsigned int mctrl)
+
+static void msm_reset(struct uart_port *port)
 {