greybus: uart: kmalloc for send_data once only

Make kmalloc for the send buffer a one time alloc based on the MTU for
a given greybus link.

The write_room for an gb_operation_sync then will be the size of the
buffer we use for a single operation.

Signed-off-by: Bryan O'Donoghue <bryan.odonoghue@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>

diff --git a/drivers/staging/greybus/uart.c b/drivers/staging/greybus/uart.c
index 928b83d..ed03ba4 100644 (file)
--- a/drivers/staging/greybus/uart.c
+++ b/drivers/staging/greybus/uart.c
@@ -42,6 +42,8 @@ struct gb_tty_line_coding {
 
 struct gb_tty {
        struct tty_port port;
+       void *buffer;
+       u32 buffer_payload_max;
        struct gb_connection *connection;
        u16 cport_id;
        unsigned int minor;
@@ -76,15 +78,13 @@ static int send_data(struct gb_tty *tty, u16 size, const u8 *data)
        if (!data || !size)
                return 0;
 
-       request = kmalloc(sizeof(*request) + size, GFP_KERNEL);
-       if (!request)
-               return -ENOMEM;
-
+       if (size > tty->buffer_payload_max)
+               size = tty->buffer_payload_max;
+       request = tty->buffer;
        request->size = cpu_to_le16(size);
        memcpy(&request->data[0], data, size);
        ret = gb_operation_sync(tty->connection, GB_UART_TYPE_SEND_DATA,
                                request, sizeof(*request) + size, NULL, 0);
-       kfree(request);
        if (ret)
                return ret;
        else
@@ -227,17 +227,13 @@ static int gb_tty_write(struct tty_struct *tty, const unsigned char *buf,
 
 static int gb_tty_write_room(struct tty_struct *tty)
 {
-//     struct gb_tty *gb_tty = tty->driver_data;
+       struct gb_tty *gb_tty = tty->driver_data;
 
-       // FIXME - how much do we want to say we have room for?
-       return 0;
+       return gb_tty->buffer_payload_max;
 }
 
 static int gb_tty_chars_in_buffer(struct tty_struct *tty)
 {
-//     struct gb_tty *gb_tty = tty->driver_data;
-
-       // FIXME - how many left to send?
        return 0;
 }
 
@@ -549,6 +545,19 @@ static int gb_uart_connection_init(struct gb_connection *connection)
        if (!gb_tty)
                return -ENOMEM;
 
+       gb_tty->buffer_payload_max =
+               gb_operation_get_payload_size_max(connection);
+       if (!gb_tty->buffer_payload_max) {
+               kfree(gb_tty);
+               return -EINVAL;
+       }
+
+       gb_tty->buffer = kzalloc(gb_tty->buffer_payload_max, GFP_KERNEL);
+       if (!gb_tty->buffer) {
+               kfree(gb_tty);
+               return -ENOMEM;
+       }
+
        gb_tty->connection = connection;
        connection->private = gb_tty;
 
@@ -600,6 +609,7 @@ error:
        release_minor(gb_tty);
 error_version:
        connection->private = NULL;
+       kfree(gb_tty->buffer);
        kfree(gb_tty);
        return retval;
 }
@@ -632,6 +642,7 @@ static void gb_uart_connection_exit(struct gb_connection *connection)
 
        tty_port_put(&gb_tty->port);
        tty_port_destroy(&gb_tty->port);
+       kfree(gb_tty->buffer);
        kfree(gb_tty);
 
        /* If last device is gone, tear down the tty structures */