[PATCH] serial: 8250_uniphier: add earlycon support

Masahiro Yamada
2015-10-22T08:39:28Z

This reuses the code of drivers/tty/serial/8250/8250_early.c except

- Overwrite device->port.iotype and device->port.regshift for
UPIO_MEM32 because of_setup_earlycon() has set them for UPIO_MEM.

- Set device->baud to zero to prevent early8250_setup() from
initializing the divisor register because port->uartclk does not
match the frequency expected by this hardware.

Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
---

drivers/tty/serial/8250/8250_uniphier.c | 24 ++++++++++++++++++++++++
1 file changed, 24 insertions(+)

diff --git a/drivers/tty/serial/8250/8250_uniphier.c b/drivers/tty/serial/8250/8250_uniphier.c
index 245edbb..c1075c5 100644
--- a/drivers/tty/serial/8250/8250_uniphier.c
+++ b/drivers/tty/serial/8250/8250_uniphier.c
@@ -13,6 +13,7 @@
*/

#include <linux/clk.h>
+#include <linux/console.h>
#include <linux/io.h>
#include <linux/module.h>
#include <linux/of.h>
@@ -34,6 +35,29 @@ struct uniphier8250_priv {
spinlock_t atomic_write_lock;
};

+#if IS_ENABLED(CONFIG_SERIAL_8250_CONSOLE)
+static int __init uniphier_early_console_setup(struct earlycon_device *device,
+ const char *options)
+{
+ if (!device->port.membase)
+ return -ENODEV;
+
+ /* This hardware always expects MMIO32 register interface. */
+ device->port.iotype = UPIO_MEM32;
+ device->port.regshift = 2;
+
+ /*
+ * Do not touch the divisor register in early_serial8250_setup();
+ * we assume it has been initialized by a boot loader.
+ */
+ device->baud = 0;
+
+ return early_serial8250_setup(device, options);
+}
+OF_EARLYCON_DECLARE(uniphier_uart, "socionext,uniphier-uart",
+ uniphier_early_console_setup);
+#endif
+
/*
* The register map is slightly different from that of 8250.
* IO callbacks must be overridden for correct access to FCR, LCR, and MCR.
--
1.9.1