ARM: CSR: add rtc i/o bridge interface for SiRFprimaII

The module is a bridge between the RTC clock domain and the CPU interface
clock domain. ARM access the register of SYSRTC, GPSRTC and PWRC through
this module.
Signed-off-by: Zhiwu Song <zhiwu.song@csr.com>
Signed-off-by: Barry Song <Baohua.Song@csr.com>
Reviewed-by: Jamie Iles <jamie@jamieiles.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>

arch/arm/boot/dts/prima2-cb.dts

@@ -363,7 +363,7 @@ rom-interface@57a00000 {
 		};
 
 		rtc-iobg {
-			compatible = "sirf,prima2-rtciobg", "simple-bus";
+			compatible = "sirf,prima2-rtciobg", "sirf-prima2-rtciobg-bus";
 			#address-cells = <1>;
 			#size-cells = <1>;
 			reg = <0x80030000 0x10000>;

arch/arm/mach-prima2/Makefile

@@ -3,5 +3,6 @@ obj-y += irq.o
 obj-y += clock.o
 obj-y += rstc.o
 obj-y += prima2.o
+obj-y += rtciobrg.o
 obj-$(CONFIG_DEBUG_LL) += lluart.o
 obj-$(CONFIG_CACHE_L2X0) += l2x0.o

arch/arm/mach-prima2/rtciobrg.c

+/*
+ * RTC I/O Bridge interfaces for CSR SiRFprimaII
+ * ARM access the registers of SYSRTC, GPSRTC and PWRC through this module
+ *
+ * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2 or later.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_device.h>
+#include <linux/of_platform.h>
+
+#define SIRFSOC_CPUIOBRG_CTRL           0x00
+#define SIRFSOC_CPUIOBRG_WRBE           0x04
+#define SIRFSOC_CPUIOBRG_ADDR           0x08
+#define SIRFSOC_CPUIOBRG_DATA           0x0c
+
+/*
+ * suspend asm codes will access this address to make system deepsleep
+ * after DRAM becomes self-refresh
+ */
+void __iomem *sirfsoc_rtciobrg_base;
+static DEFINE_SPINLOCK(rtciobrg_lock);
+
+/*
+ * symbols without lock are only used by suspend asm codes
+ * and these symbols are not exported too
+ */
+void sirfsoc_rtc_iobrg_wait_sync(void)
+{
+	while (readl_relaxed(sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_CTRL))
+		cpu_relax();
+}
+
+void sirfsoc_rtc_iobrg_besyncing(void)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtciobrg_lock, flags);
+
+	sirfsoc_rtc_iobrg_wait_sync();
+
+	spin_unlock_irqrestore(&rtciobrg_lock, flags);
+}
+EXPORT_SYMBOL_GPL(sirfsoc_rtc_iobrg_besyncing);
+
+u32 __sirfsoc_rtc_iobrg_readl(u32 addr)
+{
+	sirfsoc_rtc_iobrg_wait_sync();
+
+	writel_relaxed(0x00, sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_WRBE);
+	writel_relaxed(addr, sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_ADDR);
+	writel_relaxed(0x01, sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_CTRL);
+
+	sirfsoc_rtc_iobrg_wait_sync();
+
+	return readl_relaxed(sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_DATA);
+}
+
+u32 sirfsoc_rtc_iobrg_readl(u32 addr)
+{
+	unsigned long flags, val;
+
+	spin_lock_irqsave(&rtciobrg_lock, flags);
+
+	val = __sirfsoc_rtc_iobrg_readl(addr);
+
+	spin_unlock_irqrestore(&rtciobrg_lock, flags);
+
+	return val;
+}
+EXPORT_SYMBOL_GPL(sirfsoc_rtc_iobrg_readl);
+
+void sirfsoc_rtc_iobrg_pre_writel(u32 val, u32 addr)
+{
+	sirfsoc_rtc_iobrg_wait_sync();
+
+	writel_relaxed(0xf1, sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_WRBE);
+	writel_relaxed(addr, sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_ADDR);
+
+	writel_relaxed(val, sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_DATA);
+}
+
+void sirfsoc_rtc_iobrg_writel(u32 val, u32 addr)
+{
+	unsigned long flags;
+
+	spin_lock_irqsave(&rtciobrg_lock, flags);
+
+	sirfsoc_rtc_iobrg_pre_writel(val, addr);
+
+	writel_relaxed(0x01, sirfsoc_rtciobrg_base + SIRFSOC_CPUIOBRG_CTRL);
+
+	sirfsoc_rtc_iobrg_wait_sync();
+
+	spin_unlock_irqrestore(&rtciobrg_lock, flags);
+}
+EXPORT_SYMBOL_GPL(sirfsoc_rtc_iobrg_writel);
+
+static const struct of_device_id rtciobrg_ids[] = {
+	{ .compatible = "sirf,prima2-rtciobg" },
+	{}
+};
+
+static int __devinit sirfsoc_rtciobrg_probe(struct platform_device *op)
+{
+	struct device_node *np = op->dev.of_node;
+
+	sirfsoc_rtciobrg_base = of_iomap(np, 0);
+	if (!sirfsoc_rtciobrg_base)
+		panic("unable to map rtc iobrg registers\n");
+
+	return 0;
+}
+
+static struct platform_driver sirfsoc_rtciobrg_driver = {
+	.probe		= sirfsoc_rtciobrg_probe,
+	.driver = {
+		.name = "sirfsoc-rtciobrg",
+		.owner = THIS_MODULE,
+		.of_match_table	= rtciobrg_ids,
+	},
+};
+
+static int __init sirfsoc_rtciobrg_init(void)
+{
+	return platform_driver_register(&sirfsoc_rtciobrg_driver);
+}
+postcore_initcall(sirfsoc_rtciobrg_init);
+
+MODULE_AUTHOR("Zhiwu Song <zhiwu.song@csr.com>, "
+		"Barry Song <baohua.song@csr.com>");
+MODULE_DESCRIPTION("CSR SiRFprimaII rtc io bridge");
+MODULE_LICENSE("GPL");

include/linux/rtc/sirfsoc_rtciobrg.h

+/*
+ * RTC I/O Bridge interfaces for CSR SiRFprimaII
+ * ARM access the registers of SYSRTC, GPSRTC and PWRC through this module
+ *
+ * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
+ *
+ * Licensed under GPLv2 or later.
+ */
+#ifndef _SIRFSOC_RTC_IOBRG_H_
+#define _SIRFSOC_RTC_IOBRG_H_
+
+extern void sirfsoc_rtc_iobrg_besyncing(void);
+
+extern u32 sirfsoc_rtc_iobrg_readl(u32 addr);
+
+extern void sirfsoc_rtc_iobrg_writel(u32 val, u32 addr);
+
+#endif