x86: intel-mid: add watchdog platform code for Merrifield

This patch adds platform code for Intel Merrifield.
Since the watchdog is not part of SFI table, we have no other option but
to manually register watchdog's platform device (argh!).

Signed-off-by: David Cohen <david.a.cohen@linux.intel.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@iguana.be>

arch/x86/platform/intel-mid/device_libs/Makefile

@@ -20,3 +20,4 @@ obj-$(subst m,y,$(CONFIG_DRM_MEDFIELD)) += platform_tc35876x.o
 obj-$(subst m,y,$(CONFIG_SERIAL_MRST_MAX3110)) += platform_max3111.o
 # MISC Devices
 obj-$(subst m,y,$(CONFIG_KEYBOARD_GPIO)) += platform_gpio_keys.o
+obj-$(subst m,y,$(CONFIG_INTEL_MID_WATCHDOG)) += platform_wdt.o

arch/x86/platform/intel-mid/device_libs/platform_wdt.c

@@ -0,0 +1,72 @@
+/*
+ * platform_wdt.c: Watchdog platform library file
+ *
+ * (C) Copyright 2014 Intel Corporation
+ * Author: David Cohen <david.a.cohen@linux.intel.com>
+ *
+ * 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; version 2
+ * of the License.
+ */
+
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+#include <linux/platform_data/intel-mid_wdt.h>
+#include <asm/intel-mid.h>
+#include <asm/io_apic.h>
+
+#define TANGIER_EXT_TIMER0_MSI 15
+
+static struct platform_device wdt_dev = {
+	.name = "intel_mid_wdt",
+	.id = -1,
+};
+
+static int tangier_probe(struct platform_device *pdev)
+{
+	int ioapic;
+	int irq;
+	struct intel_mid_wdt_pdata *pdata = pdev->dev.platform_data;
+	struct io_apic_irq_attr irq_attr = { 0 };
+
+	if (!pdata)
+		return -EINVAL;
+
+	irq = pdata->irq;
+	ioapic = mp_find_ioapic(irq);
+	if (ioapic >= 0) {
+		int ret;
+		irq_attr.ioapic = ioapic;
+		irq_attr.ioapic_pin = irq;
+		irq_attr.trigger = 1;
+		/* irq_attr.polarity = 0; -> Active high */
+		ret = io_apic_set_pci_routing(NULL, irq, &irq_attr);
+		if (ret)
+			return ret;
+	} else {
+		dev_warn(&pdev->dev, "cannot find interrupt %d in ioapic\n",
+			 irq);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct intel_mid_wdt_pdata tangier_pdata = {
+	.irq = TANGIER_EXT_TIMER0_MSI,
+	.probe = tangier_probe,
+};
+
+static int __init register_mid_wdt(void)
+{
+	if (intel_mid_identify_cpu() == INTEL_MID_CPU_CHIP_TANGIER) {
+		wdt_dev.dev.platform_data = &tangier_pdata;
+		return platform_device_register(&wdt_dev);
+	}
+
+	return -ENODEV;
+}
+
+rootfs_initcall(register_mid_wdt);