ARM: add basic support for the Broadcom BCM2835 SoC

This SoC is used in the Raspberry Pi, for example.

For more details, see:
http://www.broadcom.com/products/BCM2835
http://www.raspberrypi.org/wp-content/uploads/2012/02/BCM2835-ARM-Peripherals.pdf.

Initial support is enough to boot to a serial console, execute a minimal
set of U-Boot commands, download data over a serial port, and boot a
Linux kernel. No storage or network drivers are implemented.

GPIO driver originally by Vikram Narayanan <vikram186@gmail.com>
with many fixes from myself.

Signed-off-by: Stephen Warren <swarren@wwwdotorg.org>

2 files changed, 90 insertions, 0 deletions

diff --git a/drivers/gpio/Makefile b/drivers/gpio/Makefile
index 3c67599..17f4b73 100644
--- a/drivers/gpio/Makefile
+++ b/drivers/gpio/Makefile
@@ -43,6 +43,7 @@ COBJS-$(CONFIG_MPC83XX_GPIO)	+= mpc83xx_gpio.o
 COBJS-$(CONFIG_SH_GPIO_PFC)	+= sh_pfc.o
 COBJS-$(CONFIG_OMAP_GPIO)	+= omap_gpio.o
 COBJS-$(CONFIG_DB8500_GPIO)	+= db8500_gpio.o
+COBJS-$(CONFIG_BCM2835_GPIO)	+= bcm2835_gpio.o
 
 COBJS	:= $(COBJS-y)
 SRCS 	:= $(COBJS:.o=.c)
diff --git a/drivers/gpio/bcm2835_gpio.c b/drivers/gpio/bcm2835_gpio.c
new file mode 100644
index 0000000..1d50dbd
--- /dev/null
+++ b/drivers/gpio/bcm2835_gpio.c
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C) 2012 Vikram Narayananan
+ * <vikram186@gmail.com>
+ *
+ * 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 as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * 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 <asm/gpio.h>
+#include <asm/io.h>
+
+inline int gpio_is_valid(unsigned gpio)
+{
+	return (gpio < BCM2835_GPIO_COUNT);
+}
+
+int gpio_request(unsigned gpio, const char *label)
+{
+	return !gpio_is_valid(gpio);
+}
+
+int gpio_free(unsigned gpio)
+{
+	return 0;
+}
+
+int gpio_direction_input(unsigned gpio)
+{
+	struct bcm2835_gpio_regs *reg =
+		(struct bcm2835_gpio_regs *)BCM2835_GPIO_BASE;
+	unsigned val;
+
+	val = readl(&reg->gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
+	val &= ~(BCM2835_GPIO_FSEL_MASK << BCM2835_GPIO_FSEL_SHIFT(gpio));
+	val |= (BCM2835_GPIO_INPUT << BCM2835_GPIO_FSEL_SHIFT(gpio));
+	writel(val, &reg->gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
+
+	return 0;
+}
+
+int gpio_direction_output(unsigned gpio, int value)
+{
+	struct bcm2835_gpio_regs *reg =
+		(struct bcm2835_gpio_regs *)BCM2835_GPIO_BASE;
+	unsigned val;
+
+	gpio_set_value(gpio, value);
+
+	val = readl(&reg->gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
+	val &= ~(BCM2835_GPIO_FSEL_MASK << BCM2835_GPIO_FSEL_SHIFT(gpio));
+	val |= (BCM2835_GPIO_OUTPUT << BCM2835_GPIO_FSEL_SHIFT(gpio));
+	writel(val, &reg->gpfsel[BCM2835_GPIO_FSEL_BANK(gpio)]);
+
+	return 0;
+}
+
+int gpio_get_value(unsigned gpio)
+{
+	struct bcm2835_gpio_regs *reg =
+		(struct bcm2835_gpio_regs *)BCM2835_GPIO_BASE;
+	unsigned val;
+
+	val = readl(&reg->gplev[BCM2835_GPIO_COMMON_BANK(gpio)]);
+
+	return (val >> BCM2835_GPIO_COMMON_SHIFT(gpio)) & 0x1;
+}
+
+int gpio_set_value(unsigned gpio, int value)
+{
+	struct bcm2835_gpio_regs *reg =
+		(struct bcm2835_gpio_regs *)BCM2835_GPIO_BASE;
+	u32 *output_reg = value ? reg->gpset : reg->gpclr;
+
+	writel(1 << BCM2835_GPIO_COMMON_SHIFT(gpio),
+				&output_reg[BCM2835_GPIO_COMMON_BANK(gpio)]);
+
+	return 0;
+}