MIPS: Add RTC support for Loongson1C board

The patch adds RTC support for Loongson1C board, and enable the external
crystal when the RTC is first powered up.

Signed-off-by: Yang Ling <gnaygnil@gmail.com>
Cc: keguang.zhang@gmail.com
Cc: linux-mips@linux-mips.org
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/14214/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/include/asm/mach-loongson32/platform.h

@@ -30,5 +30,6 @@ void __init ls1x_clk_init(void);
 void __init ls1x_dma_set_platdata(struct plat_ls1x_dma *pdata);
 void __init ls1x_nand_set_platdata(struct plat_ls1x_nand *pdata);
 void __init ls1x_serial_set_uartclk(struct platform_device *pdev);
+void __init ls1x_rtc_set_extclk(struct platform_device *pdev);
 
 #endif /* __ASM_MACH_LOONGSON32_PLATFORM_H */

arch/mips/loongson32/common/platform.c

@@ -23,6 +23,10 @@
 #include <dma.h>
 #include <nand.h>
 
+#define LS1X_RTC_CTRL	((void __iomem *)KSEG1ADDR(LS1X_RTC_BASE + 0x40))
+#define RTC_EXTCLK_OK	(BIT(5) | BIT(8))
+#define RTC_EXTCLK_EN	BIT(8)
+
 /* 8250/16550 compatible UART */
 #define LS1X_UART(_id)						\
 	{							\
@@ -66,6 +70,15 @@ void __init ls1x_serial_set_uartclk(struct platform_device *pdev)
 		p->uartclk = clk_get_rate(clk);
 }
 
+void __init ls1x_rtc_set_extclk(struct platform_device *pdev)
+{
+	u32 val;
+
+	val = __raw_readl(LS1X_RTC_CTRL);
+	if (!(val & RTC_EXTCLK_OK))
+		__raw_writel(val | RTC_EXTCLK_EN, LS1X_RTC_CTRL);
+}
+
 /* CPUFreq */
 static struct plat_ls1x_cpufreq ls1x_cpufreq_pdata = {
 	.clk_name	= "cpu_clk",

arch/mips/loongson32/ls1c/Makefile

@@ -1,5 +1,5 @@
 #
-# Makefile for loongson1B based machines.
+# Makefile for loongson1C based machines.
 #
 
 obj-y += board.o

arch/mips/loongson32/ls1c/board.c

@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2016 Ling Yang <gnaygnil@gmail.com>
+ * Copyright (c) 2016 Yang Ling <gnaygnil@gmail.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
@@ -12,17 +12,16 @@
 static struct platform_device *ls1c_platform_devices[] __initdata = {
 	&ls1x_uart_pdev,
 	&ls1x_eth0_pdev,
+	&ls1x_rtc_pdev,
 };
 
 static int __init ls1c_platform_init(void)
 {
-	int err;
-
 	ls1x_serial_set_uartclk(&ls1x_uart_pdev);
+	ls1x_rtc_set_extclk(&ls1x_rtc_pdev);
 
-	err = platform_add_devices(ls1c_platform_devices,
+	return platform_add_devices(ls1c_platform_devices,
 				   ARRAY_SIZE(ls1c_platform_devices));
-	return err;
 }
 
 arch_initcall(ls1c_platform_init);