[RFC 2/8] serial: add driver for Canon DIGIC UART

[Antony Pavlov]

Signed-off-by: Antony Pavlov <antonynpavlov at gmail.com>
---
 drivers/serial/Kconfig        |   4 ++
 drivers/serial/Makefile       |   1 +
 drivers/serial/serial_digic.c | 131 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 136 insertions(+)
 create mode 100644 drivers/serial/serial_digic.c

diff --git a/drivers/serial/Kconfig b/drivers/serial/Kconfig
index 11fc155..541350d 100644
--- a/drivers/serial/Kconfig
+++ b/drivers/serial/Kconfig
@@ -122,4 +122,8 @@ config DRIVER_SERIAL_CADENCE
 	help
 	  Say Y here if you have a Cadence serial IP core.
 
+config DRIVER_SERIAL_DIGIC
+	bool "Canon DIGIC serial driver"
+	depends on ARCH_DIGIC
+
 endmenu
diff --git a/drivers/serial/Makefile b/drivers/serial/Makefile
index 93790b5..485a3ef 100644
--- a/drivers/serial/Makefile
+++ b/drivers/serial/Makefile
@@ -17,3 +17,4 @@ obj-$(CONFIG_DRIVER_SERIAL_PXA)			+= serial_pxa.o
 obj-$(CONFIG_DRIVER_SERIAL_OMAP4_USBBOOT)	+= serial_omap4_usbboot.o
 obj-$(CONFIG_DRIVER_SERIAL_AUART)		+= serial_auart.o
 obj-$(CONFIG_DRIVER_SERIAL_CADENCE)		+= serial_cadence.o
+obj-$(CONFIG_DRIVER_SERIAL_DIGIC)		+= serial_digic.o
diff --git a/drivers/serial/serial_digic.c b/drivers/serial/serial_digic.c
new file mode 100644
index 0000000..938172f
--- /dev/null
+++ b/drivers/serial/serial_digic.c
@@ -0,0 +1,131 @@
+/*
+ * Copyright (C) 2013 Antony Pavlov <antonynpavlov at gmail.com>
+ *
+ * This file is part of barebox.
+ * See file CREDITS for list of people who contributed to this project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <common.h>
+#include <init.h>
+#include <malloc.h>
+#include <io.h>
+
+/* Serial interface registers offsets */
+#define UART_TX	0x0
+#define UART_RX	0x4
+#define UART_ST	0x14
+ #define UART_ST_RX_RDY	1
+ #define UART_ST_TX_RDY	2
+
+/*
+ * This driver is based on the "Serial terminal" docs here:
+ *  http://magiclantern.wikia.com/wiki/Register_Map#Misc_Registers
+ *
+ * See also disassembler output for Canon A1100IS firmware
+ * (version a1100_100c):
+ *   * a outc-like function can be found at address 0xffff18f0;
+ *   * a getc-like function can be found at address 0xffff192c.
+ */
+
+static inline uint32_t digic_serial_readl(struct console_device *cdev, uint32_t off)
+{
+	void *digic = cdev->dev->priv;
+
+	return readl(digic + off);
+}
+
+static inline void digic_serial_writel(struct console_device *cdev, uint32_t val,
+			  uint32_t off)
+{
+	void *digic = cdev->dev->priv;
+
+	writel(val, digic + off);
+}
+
+static int digic_serial_setbaudrate(struct console_device *cdev, int baudrate)
+{
+	/* FIXME: empty */
+
+	return 0;
+}
+
+static void digic_serial_putc(struct console_device *cdev, char c)
+{
+	while (!(digic_serial_readl(cdev, UART_ST) & UART_ST_TX_RDY))
+		; /* noop */
+
+	digic_serial_writel(cdev, 0x06, UART_ST);
+	digic_serial_writel(cdev, c, UART_TX);
+}
+
+static int digic_serial_getc(struct console_device *cdev)
+{
+	while (!(digic_serial_readl(cdev, UART_ST) & UART_ST_RX_RDY))
+		; /* noop */
+
+	digic_serial_writel(cdev, 0x01, UART_ST);
+
+	return digic_serial_readl(cdev, UART_RX);
+}
+
+static int digic_serial_tstc(struct console_device *cdev)
+{
+	return ((digic_serial_readl(cdev, UART_ST) & UART_ST_RX_RDY) != 0);
+
+	/*
+	 * Canon folks use additional check, something like this:
+	 *
+	 *		if (digic_serial_readl(cdev, UART_ST) & 0x38) {
+	 *			digic_serial_writel(cdev, 0x38, UART_ST);
+	 *			return 0;
+	 *		}
+	 *
+	 * But I know nothing about these magic bits in the status regster...
+	 *
+	*/
+}
+
+static int digic_serial_probe(struct device_d *dev)
+{
+	struct console_device *cdev;
+
+	cdev = xzalloc(sizeof(struct console_device));
+	dev->priv = dev_request_mem_region(dev, 0);
+	cdev->dev = dev;
+	cdev->f_caps = CONSOLE_STDIN | CONSOLE_STDOUT | CONSOLE_STDERR;
+	cdev->tstc = &digic_serial_tstc;
+	cdev->putc = &digic_serial_putc;
+	cdev->getc = &digic_serial_getc;
+	cdev->setbrg = &digic_serial_setbaudrate;
+
+	/* FIXME: need digic_init_port(cdev); */
+
+	console_register(cdev);
+
+	return 0;
+}
+
+static __maybe_unused struct of_device_id digic_serial_dt_ids[] = {
+	{
+		.compatible = "canon,digic-serial",
+	}, {
+		/* sentinel */
+	}
+};
+
+static struct driver_d digic_serial_driver = {
+	.name  = "digic-serial",
+	.probe = digic_serial_probe,
+	.of_compatible = DRV_OF_COMPAT(digic_serial_dt_ids),
+};
+console_platform_driver(digic_serial_driver);
-- 
1.8.4.rc3