soc: mediatek: Add infracfg misc driver support

This adds support for some miscellaneous bits of the infracfg controller.
The mtk_infracfg_set/clear_bus_protection functions are necessary for
the scpsys power domain driver to handle the bus protection bits which
are contained in the infacfg register space.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Reviewed-by: Daniel Kurtz <djkurtz@chromium.org>
Signed-off-by: Matthias Brugger <matthias.bgg@gmail.com>

drivers/soc/mediatek/Kconfig

@@ -1,6 +1,15 @@
 #
 # MediaTek SoC drivers
 #
+config MTK_INFRACFG
+	bool "MediaTek INFRACFG Support"
+	depends on ARCH_MEDIATEK || COMPILE_TEST
+	select REGMAP
+	help
+	  Say yes here to add support for the MediaTek INFRACFG controller. The
+	  INFRACFG controller contains various infrastructure registers not
+	  directly associated to any device.
+
 config MTK_PMIC_WRAP
 	tristate "MediaTek PMIC Wrapper Support"
 	depends on ARCH_MEDIATEK

drivers/soc/mediatek/Makefile

@@ -1 +1,2 @@
+obj-$(CONFIG_MTK_INFRACFG) += mtk-infracfg.o
 obj-$(CONFIG_MTK_PMIC_WRAP) += mtk-pmic-wrap.o

drivers/soc/mediatek/mtk-infracfg.c

@@ -0,0 +1,91 @@
+/*
+ * Copyright (c) 2015 Pengutronix, Sascha Hauer <kernel@pengutronix.de>
+ *
+ * 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.
+ *
+ * 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.
+ */
+
+#include <linux/export.h>
+#include <linux/jiffies.h>
+#include <linux/regmap.h>
+#include <linux/soc/mediatek/infracfg.h>
+#include <asm/processor.h>
+
+#define INFRA_TOPAXI_PROTECTEN		0x0220
+#define INFRA_TOPAXI_PROTECTSTA1	0x0228
+
+/**
+ * mtk_infracfg_set_bus_protection - enable bus protection
+ * @regmap: The infracfg regmap
+ * @mask: The mask containing the protection bits to be enabled.
+ *
+ * This function enables the bus protection bits for disabled power
+ * domains so that the system does not hang when some unit accesses the
+ * bus while in power down.
+ */
+int mtk_infracfg_set_bus_protection(struct regmap *infracfg, u32 mask)
+{
+	unsigned long expired;
+	u32 val;
+	int ret;
+
+	regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, mask);
+
+	expired = jiffies + HZ;
+
+	while (1) {
+		ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
+		if (ret)
+			return ret;
+
+		if ((val & mask) == mask)
+			break;
+
+		cpu_relax();
+		if (time_after(jiffies, expired))
+			return -EIO;
+	}
+
+	return 0;
+}
+
+/**
+ * mtk_infracfg_clear_bus_protection - disable bus protection
+ * @regmap: The infracfg regmap
+ * @mask: The mask containing the protection bits to be disabled.
+ *
+ * This function disables the bus protection bits previously enabled with
+ * mtk_infracfg_set_bus_protection.
+ */
+int mtk_infracfg_clear_bus_protection(struct regmap *infracfg, u32 mask)
+{
+	unsigned long expired;
+	int ret;
+
+	regmap_update_bits(infracfg, INFRA_TOPAXI_PROTECTEN, mask, 0);
+
+	expired = jiffies + HZ;
+
+	while (1) {
+		u32 val;
+
+		ret = regmap_read(infracfg, INFRA_TOPAXI_PROTECTSTA1, &val);
+		if (ret)
+			return ret;
+
+		if (!(val & mask))
+			break;
+
+		cpu_relax();
+		if (time_after(jiffies, expired))
+			return -EIO;
+	}
+
+	return 0;
+}