Add GPIO driver for BCM2835 SoC

Driver for BCM2835 SoC. This gives the basic functionality of setting/clearing the output.

Signed-off-by Vikram Narayanan<[email protected]>

---
  arch/arm/include/asm/arch-bcm2835/gpio.h |   71 ++++++++++++++++++++++++
  drivers/gpio/Makefile                    |    1 +
  drivers/gpio/bcm2835_gpio.c              |   88 ++++++++++++++++++++++++++++++
  3 files changed, 160 insertions(+), 0 deletions(-)

create mode 100644 arch/arm/include/asm/arch-bcm2835/gpio.h create mode 100644 drivers/gpio/bcm2835_gpio.c

arch/arm/include/asm/arch-bcm2835/gpio.h new file +18 -0

new file mode 100644
index 0000000..515456a
@@ -0,0 +1,71 @@
+/*
+ * Copyright (C) 2012 Vikram Narayananan
+ *<[email protected]>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License

arch/arm/include/asm/arch-bcm2835/gpio.h new file +43 -0

+
+#define BCM2835_GPIO_FSEL_MASK	0x7
+#define BCM2835_GPIO_INPUT		0x0
+#define BCM2835_GPIO_OUTPUT		0x1
+#define BCM2835_GPIO_ALT0		0x2
+#define BCM2835_GPIO_ALT1		0x3
+#define BCM2835_GPIO_ALT2		0x4
+#define BCM2835_GPIO_ALT3		0x5
+#define BCM2835_GPIO_ALT4		0x6
+#define BCM2835_GPIO_ALT5		0x7
+
+#define BCM2835_GPIO_COMMON_BANK(gpio)			((gpio<  32) ? 0 : 1)
+#define BCM2835_GPIO_COMMON_SHIFT(gpio)		(gpio&  0x1f)
+
+#define BCM2835_GPIO_FSEL_BANK(gpio)	(gpio / 10)
+#define BCM2835_GPIO_FSEL_SHIFT(gpio)	((gpio % 10) * 3)
+
+struct bcm_gpio_regs {
+	u32 gpfsel[6];
+	u32 reserved1;
+	u32 gpset[2];
+	u32 reserved2;
+	u32 gpclr[2];
+	u32 reserved3;
+	u32 gplev[2];
+	u32 reserved4;
+	u32 gpeds[2];
+	u32 reserved5;
+	u32 gpren[2];
+	u32 reserved6;
+	u32 gpfen[2];
+	u32 reserved7;
+	u32 gphen[2];
+	u32 reserved8;
+	u32 gplen[2];
+	u32 reserved9;
+	u32 gparen[2];
+	u32 reserved10;
+	u32 gppud;
+	u32 gppudclk[2];
+};
+
+#endif /* _BCM2835_GPIO_H_ */

drivers/gpio/Makefile +1 -0

index 32a2474..8d2f2b2 100644
@@ -40,6 +40,7 @@ COBJS-$(CONFIG_TEGRA_GPIO)	+= tegra_gpio.o
  COBJS-$(CONFIG_DA8XX_GPIO)	+= da8xx_gpio.o
  COBJS-$(CONFIG_ALTERA_PIO)	+= altera_pio.o
  COBJS-$(CONFIG_MPC83XX_GPIO)	+= mpc83xx_gpio.o
+COBJS-$(CONFIG_BCM2835_GPIO)	+= bcm2835_gpio.o
 
  COBJS	:= $(COBJS-y)
  SRCS 	:= $(COBJS:.o=.c)

drivers/gpio/bcm2835_gpio.c new file +88 -0

new file mode 100644
index 0000000..eb02efa
@@ -0,0 +1,88 @@
+/*
+ * Copyright (C) 2012 Vikram Narayananan
+ *<[email protected]>
+ *
+ * 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.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#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 bcm_gpio_regs *reg = (struct bcm_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)]);
+	}
+
+int gpio_direction_output(unsigned gpio, int value)
+{
+	struct bcm_gpio_regs *reg = (struct bcm_gpio_regs *)BCM2835_GPIO_BASE;
+	unsigned val;
+
+	if (value)
+		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)]);
+}
+
+int gpio_get_value(unsigned gpio)
+{
+	struct bcm_gpio_regs *reg = (struct bcm_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 bcm_gpio_regs *reg = (struct bcm_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;
+}
+

Also, add the driver to the raspberrypi default config

Review

Quoted 6 lines · Vikram Narayanan

Driver for BCM2835 SoC. This gives the basic functionality of setting/clearing the output.

(quoted diff) +1 -0

 
+#define BCM2835_GPIO_COUNT    53

GPIO count should be 54 to make the gpio_is_valid work correctly when the gpio is 53.
Will fix in v4.