MIPS: Add initial support for the Atheros AR71XX/AR724X/AR931X SoCs

This patch adds initial support for various Atheros SoCs based on the
MIPS 24Kc core. The following models are supported at the moment:

  - AR7130
  - AR7141
  - AR7161
  - AR9130
  - AR9132
  - AR7240
  - AR7241
  - AR7242

The current patch contains minimal support only, but the resulting
kernel can boot into user-space with using of an initramfs image on
various boards which are using these SoCs. Support for more built-in
devices and individual boards will be implemented in further patches.

Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: Imre Kaloz <kaloz@openwrt.org>
Cc: linux-mips@linux-mips.org
Cc: Luis R. Rodriguez <lrodriguez@atheros.com>
Cc: Cliff Holden <Cliff.Holden@Atheros.com>
Cc: Kathy Giori <Kathy.Giori@Atheros.com>
Patchwork: https://patchwork.linux-mips.org/patch/1947/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>

arch/mips/ath79/clock.c

@@ -0,0 +1,183 @@
+/*
+ *  Atheros AR71XX/AR724X/AR913X common routines
+ *
+ *  Copyright (C) 2011 Gabor Juhos <juhosg@openwrt.org>
+ *
+ *  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/init.h>
+#include <linux/err.h>
+#include <linux/clk.h>
+
+#include <asm/mach-ath79/ath79.h>
+#include <asm/mach-ath79/ar71xx_regs.h>
+#include "common.h"
+
+#define AR71XX_BASE_FREQ	40000000
+#define AR724X_BASE_FREQ	5000000
+#define AR913X_BASE_FREQ	5000000
+
+struct clk {
+	unsigned long rate;
+};
+
+static struct clk ath79_ref_clk;
+static struct clk ath79_cpu_clk;
+static struct clk ath79_ddr_clk;
+static struct clk ath79_ahb_clk;
+static struct clk ath79_wdt_clk;
+static struct clk ath79_uart_clk;
+
+static void __init ar71xx_clocks_init(void)
+{
+	u32 pll;
+	u32 freq;
+	u32 div;
+
+	ath79_ref_clk.rate = AR71XX_BASE_FREQ;
+
+	pll = ath79_pll_rr(AR71XX_PLL_REG_CPU_CONFIG);
+
+	div = ((pll >> AR71XX_PLL_DIV_SHIFT) & AR71XX_PLL_DIV_MASK) + 1;
+	freq = div * ath79_ref_clk.rate;
+
+	div = ((pll >> AR71XX_CPU_DIV_SHIFT) & AR71XX_CPU_DIV_MASK) + 1;
+	ath79_cpu_clk.rate = freq / div;
+
+	div = ((pll >> AR71XX_DDR_DIV_SHIFT) & AR71XX_DDR_DIV_MASK) + 1;
+	ath79_ddr_clk.rate = freq / div;
+
+	div = (((pll >> AR71XX_AHB_DIV_SHIFT) & AR71XX_AHB_DIV_MASK) + 1) * 2;
+	ath79_ahb_clk.rate = ath79_cpu_clk.rate / div;
+
+	ath79_wdt_clk.rate = ath79_ahb_clk.rate;
+	ath79_uart_clk.rate = ath79_ahb_clk.rate;
+}
+
+static void __init ar724x_clocks_init(void)
+{
+	u32 pll;
+	u32 freq;
+	u32 div;
+
+	ath79_ref_clk.rate = AR724X_BASE_FREQ;
+	pll = ath79_pll_rr(AR724X_PLL_REG_CPU_CONFIG);
+
+	div = ((pll >> AR724X_PLL_DIV_SHIFT) & AR724X_PLL_DIV_MASK);
+	freq = div * ath79_ref_clk.rate;
+
+	div = ((pll >> AR724X_PLL_REF_DIV_SHIFT) & AR724X_PLL_REF_DIV_MASK);
+	freq *= div;
+
+	ath79_cpu_clk.rate = freq;
+
+	div = ((pll >> AR724X_DDR_DIV_SHIFT) & AR724X_DDR_DIV_MASK) + 1;
+	ath79_ddr_clk.rate = freq / div;
+
+	div = (((pll >> AR724X_AHB_DIV_SHIFT) & AR724X_AHB_DIV_MASK) + 1) * 2;
+	ath79_ahb_clk.rate = ath79_cpu_clk.rate / div;
+
+	ath79_wdt_clk.rate = ath79_ahb_clk.rate;
+	ath79_uart_clk.rate = ath79_ahb_clk.rate;
+}
+
+static void __init ar913x_clocks_init(void)
+{
+	u32 pll;
+	u32 freq;
+	u32 div;
+
+	ath79_ref_clk.rate = AR913X_BASE_FREQ;
+	pll = ath79_pll_rr(AR913X_PLL_REG_CPU_CONFIG);
+
+	div = ((pll >> AR913X_PLL_DIV_SHIFT) & AR913X_PLL_DIV_MASK);
+	freq = div * ath79_ref_clk.rate;
+
+	ath79_cpu_clk.rate = freq;
+
+	div = ((pll >> AR913X_DDR_DIV_SHIFT) & AR913X_DDR_DIV_MASK) + 1;
+	ath79_ddr_clk.rate = freq / div;
+
+	div = (((pll >> AR913X_AHB_DIV_SHIFT) & AR913X_AHB_DIV_MASK) + 1) * 2;
+	ath79_ahb_clk.rate = ath79_cpu_clk.rate / div;
+
+	ath79_wdt_clk.rate = ath79_ahb_clk.rate;
+	ath79_uart_clk.rate = ath79_ahb_clk.rate;
+}
+
+void __init ath79_clocks_init(void)
+{
+	if (soc_is_ar71xx())
+		ar71xx_clocks_init();
+	else if (soc_is_ar724x())
+		ar724x_clocks_init();
+	else if (soc_is_ar913x())
+		ar913x_clocks_init();
+	else
+		BUG();
+
+	pr_info("Clocks: CPU:%lu.%03luMHz, DDR:%lu.%03luMHz, AHB:%lu.%03luMHz, "
+		"Ref:%lu.%03luMHz",
+		ath79_cpu_clk.rate / 1000000,
+		(ath79_cpu_clk.rate / 1000) % 1000,
+		ath79_ddr_clk.rate / 1000000,
+		(ath79_ddr_clk.rate / 1000) % 1000,
+		ath79_ahb_clk.rate / 1000000,
+		(ath79_ahb_clk.rate / 1000) % 1000,
+		ath79_ref_clk.rate / 1000000,
+		(ath79_ref_clk.rate / 1000) % 1000);
+}
+
+/*
+ * Linux clock API
+ */
+struct clk *clk_get(struct device *dev, const char *id)
+{
+	if (!strcmp(id, "ref"))
+		return &ath79_ref_clk;
+
+	if (!strcmp(id, "cpu"))
+		return &ath79_cpu_clk;
+
+	if (!strcmp(id, "ddr"))
+		return &ath79_ddr_clk;
+
+	if (!strcmp(id, "ahb"))
+		return &ath79_ahb_clk;
+
+	if (!strcmp(id, "wdt"))
+		return &ath79_wdt_clk;
+
+	if (!strcmp(id, "uart"))
+		return &ath79_uart_clk;
+
+	return ERR_PTR(-ENOENT);
+}
+EXPORT_SYMBOL(clk_get);
+
+int clk_enable(struct clk *clk)
+{
+	return 0;
+}
+EXPORT_SYMBOL(clk_enable);
+
+void clk_disable(struct clk *clk)
+{
+}
+EXPORT_SYMBOL(clk_disable);
+
+unsigned long clk_get_rate(struct clk *clk)
+{
+	return clk->rate;
+}
+EXPORT_SYMBOL(clk_get_rate);
+
+void clk_put(struct clk *clk)
+{
+}
+EXPORT_SYMBOL(clk_put);