[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>

4 files changed, 102 insertions, 17 deletions

diff --git a/arch/arm/mach-pxa/Makefile b/arch/arm/mach-pxa/Makefile
index 0e6d05bb81aa..c9e66fbe622e 100644
--- a/arch/arm/mach-pxa/Makefile
+++ b/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
 
diff --git a/arch/arm/mach-pxa/reset.c b/arch/arm/mach-pxa/reset.c
new file mode 100644
index 000000000000..551f313c94df
--- /dev/null
+++ b/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;
+        }
+}
+
diff --git a/include/asm-arm/arch-pxa/hardware.h b/include/asm-arm/arch-pxa/hardware.h
index e25558faa5a4..5547ec797ad0 100644
--- a/include/asm-arm/arch-pxa/hardware.h
+++ b/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)
diff --git a/include/asm-arm/arch-pxa/system.h b/include/asm-arm/arch-pxa/system.h
index 9aa6c2e939e8..14894ae3fa67 100644
--- a/include/asm-arm/arch-pxa/system.h
+++ b/include/asm-arm/arch-pxa/system.h
@@ -20,19 +20,4 @@ static inline void arch_idle(void)
 }
 
 
-static inline 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 */
-        }
-}
-
+void arch_reset(char mode);