tty: serial: msm: Add earlycon support

Add support for DT based and command line based early console on platforms
with the msm serial hardware.

Cc: Rob Herring <robh@kernel.org>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 63 insertions, 12 deletions

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 02a896f4dbcd..649b784081c7 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1070,6 +1070,7 @@ config SERIAL_MSM_CONSOLE
         bool "MSM serial console support"
         depends on SERIAL_MSM=y
         select SERIAL_CORE_CONSOLE
+        select SERIAL_EARLYCON
 
 config SERIAL_MSM_HS
         tristate "MSM UART High Speed: Serial Driver"
diff --git a/drivers/tty/serial/msm_serial.c b/drivers/tty/serial/msm_serial.c
index 4f9640d0b1bb..4b6c78331a64 100644
--- a/drivers/tty/serial/msm_serial.c
+++ b/drivers/tty/serial/msm_serial.c
@@ -845,22 +845,15 @@ static inline struct uart_port *get_port_from_line(unsigned int line)
 }
 
 #ifdef CONFIG_SERIAL_MSM_CONSOLE
-static void msm_console_write(struct console *co, const char *s,
-                              unsigned int count)
+static void __msm_console_write(struct uart_port *port, const char *s,
+                                unsigned int count, bool is_uartdm)
 {
         int i;
-        struct uart_port *port;
-        struct msm_port *msm_port;
         int num_newlines = 0;
         bool replaced = false;
         void __iomem *tf;
 
-        BUG_ON(co->index < 0 || co->index >= UART_NR);
-
-        port = get_port_from_line(co->index);
-        msm_port = UART_TO_MSM(port);
-
-        if (msm_port->is_uartdm)
+        if (is_uartdm)
                 tf = port->membase + UARTDM_TF;
         else
                 tf = port->membase + UART_TF;
@@ -872,7 +865,7 @@ static void msm_console_write(struct console *co, const char *s,
         count += num_newlines;
 
         spin_lock(&port->lock);
-        if (msm_port->is_uartdm)
+        if (is_uartdm)
                 reset_dm_count(port, count);
 
         i = 0;
@@ -881,7 +874,7 @@ static void msm_console_write(struct console *co, const char *s,
                 unsigned int num_chars;
                 char buf[4] = { 0 };
 
-                if (msm_port->is_uartdm)
+                if (is_uartdm)
                         num_chars = min(count - i, (unsigned int)sizeof(buf));
                 else
                         num_chars = 1;
@@ -910,6 +903,20 @@ static void msm_console_write(struct console *co, const char *s,
         spin_unlock(&port->lock);
 }
 
+static void msm_console_write(struct console *co, const char *s,
+                              unsigned int count)
+{
+        struct uart_port *port;
+        struct msm_port *msm_port;
+
+        BUG_ON(co->index < 0 || co->index >= UART_NR);
+
+        port = get_port_from_line(co->index);
+        msm_port = UART_TO_MSM(port);
+
+        __msm_console_write(port, s, count, msm_port->is_uartdm);
+}
+
 static int __init msm_console_setup(struct console *co, char *options)
 {
         struct uart_port *port;
@@ -952,6 +959,49 @@ static int __init msm_console_setup(struct console *co, char *options)
         return uart_set_options(port, co, baud, parity, bits, flow);
 }
 
+static void
+msm_serial_early_write(struct console *con, const char *s, unsigned n)
+{
+        struct earlycon_device *dev = con->data;
+
+        __msm_console_write(&dev->port, s, n, false);
+}
+
+static int __init
+msm_serial_early_console_setup(struct earlycon_device *device, const char *opt)
+{
+        if (!device->port.membase)
+                return -ENODEV;
+
+        device->con->write = msm_serial_early_write;
+        return 0;
+}
+EARLYCON_DECLARE(msm_serial, msm_serial_early_console_setup);
+OF_EARLYCON_DECLARE(msm_serial, "qcom,msm-uart",
+                    msm_serial_early_console_setup);
+
+static void
+msm_serial_early_write_dm(struct console *con, const char *s, unsigned n)
+{
+        struct earlycon_device *dev = con->data;
+
+        __msm_console_write(&dev->port, s, n, true);
+}
+
+static int __init
+msm_serial_early_console_setup_dm(struct earlycon_device *device,
+                                  const char *opt)
+{
+        if (!device->port.membase)
+                return -ENODEV;
+
+        device->con->write = msm_serial_early_write_dm;
+        return 0;
+}
+EARLYCON_DECLARE(msm_serial_dm, msm_serial_early_console_setup_dm);
+OF_EARLYCON_DECLARE(msm_serial_dm, "qcom,msm-uartdm",
+                    msm_serial_early_console_setup_dm);
+
 static struct uart_driver msm_uart_driver;
 
 static struct console msm_console = {