[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>

1 files changed, 95 insertions, 0 deletions

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;
+        }
+}
+