[ARM] 5047/2: Support resetting by asserting GPIO pin

This adds support for resetting via assertion of GPIO pin.
This e.g. is used on Sharp Zaurus SL-6000.

Signed-off-by: Dmitry Baryshkov <dbaryshkov@gmail.com>
Acked-by: Eric Miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

arch/arm/mach-pxa/Makefile

@@ -4,7 +4,7 @@
 
 # Common support (must be linked before board specific support)
 obj-y				+= clock.o devices.o generic.o irq.o dma.o \
-				   time.o gpio.o
+				   time.o gpio.o reset.o
 obj-$(CONFIG_PM)		+= pm.o sleep.o standby.o
 obj-$(CONFIG_CPU_FREQ)		+= cpu-pxa.o
 

arch/arm/mach-pxa/reset.c

@@ -0,0 +1,95 @@
+/*
+ * 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.
+ */
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/delay.h>
+#include <linux/gpio.h>
+#include <asm/io.h>
+#include <asm/proc-fns.h>
+
+#include <asm/arch/pxa-regs.h>
+
+static void do_hw_reset(void);
+
+static int reset_gpio = -1;
+
+int init_gpio_reset(int gpio)
+{
+	int rc;
+
+	rc = gpio_request(gpio, "reset generator");
+	if (rc) {
+		printk(KERN_ERR "Can't request reset_gpio\n");
+		goto out;
+	}
+
+	rc = gpio_direction_input(gpio);
+	if (rc) {
+		printk(KERN_ERR "Can't configure reset_gpio for input\n");
+		gpio_free(gpio);
+		goto out;
+	}
+
+out:
+	if (!rc)
+		reset_gpio = gpio;
+
+	return rc;
+}
+
+/*
+ * Trigger GPIO reset.
+ * This covers various types of logic connecting gpio pin
+ * to RESET pins (nRESET or GPIO_RESET):
+ */
+static void do_gpio_reset(void)
+{
+	BUG_ON(reset_gpio == -1);
+
+	/* drive it low */
+	gpio_direction_output(reset_gpio, 0);
+	mdelay(2);
+	/* rising edge or drive high */
+	gpio_set_value(reset_gpio, 1);
+	mdelay(2);
+	/* falling edge */
+	gpio_set_value(reset_gpio, 0);
+
+	/* give it some time */
+	mdelay(10);
+
+	WARN_ON(1);
+	/* fallback */
+	do_hw_reset();
+}
+
+static void do_hw_reset(void)
+{
+	/* Initialize the watchdog and let it fire */
+	OWER = OWER_WME;
+	OSSR = OSSR_M3;
+	OSMR3 = OSCR + 368640;	/* ... in 100 ms */
+}
+
+void arch_reset(char mode)
+{
+	if (cpu_is_pxa2xx())
+		RCSR = RCSR_HWR | RCSR_WDR | RCSR_SMR | RCSR_GPR;
+
+	switch (mode) {
+	case 's':
+		/* Jump into ROM at address 0 */
+		cpu_reset(0);
+		break;
+	case 'h':
+		do_hw_reset();
+		break;
+	case 'g':
+		do_gpio_reset();
+		break;
+	}
+}
+

include/asm-arm/arch-pxa/hardware.h

@@ -205,6 +205,11 @@ static inline void __deprecated pxa_set_cken(int clock, int enable)
  */
 extern unsigned int get_memclk_frequency_10khz(void);
 
+/*
+ * register GPIO as reset generator
+ */
+extern int init_gpio_reset(int gpio);
+
 #endif
 
 #if defined(CONFIG_MACH_ARMCORE) && defined(CONFIG_PCI)

include/asm-arm/arch-pxa/system.h

@@ -20,19 +20,4 @@ static inline void arch_idle(void)
 }
 
 
-static inline void arch_reset(char mode)
+void arch_reset(char mode);
-{
-	if (cpu_is_pxa2xx())
-		RCSR = RCSR_HWR | RCSR_WDR | RCSR_SMR | RCSR_GPR;
-
-	if (mode == 's') {
-		/* Jump into ROM at address 0 */
-		cpu_reset(0);
-	} else {
-		/* Initialize the watchdog and let it fire */
-		OWER = OWER_WME;
-		OSSR = OSSR_M3;
-		OSMR3 = OSCR + 368640;	/* ... in 100 ms */
-	}
-}
-