[ARM] 3634/1: ep93xx: initial implementation of the clk_* API

Patch from Lennert Buytenhek

Add an initial implementation of the clk_* API for the cirrus ep93xx
to the tree.  The initial implementation is somewhat minimal, with the
intention of extending it as we go along.

Signed-off-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

3 files changed, 159 insertions, 1 deletions

diff --git a/arch/arm/mach-ep93xx/Makefile b/arch/arm/mach-ep93xx/Makefile
index 5393af989e94..05a48a21038e 100644
--- a/arch/arm/mach-ep93xx/Makefile
+++ b/arch/arm/mach-ep93xx/Makefile
@@ -1,7 +1,7 @@
 #
 # Makefile for the linux kernel.
 #
-obj-y                   := core.o
+obj-y                   := core.o clock.o
 obj-m                   :=
 obj-n                   :=
 obj-                    :=
diff --git a/arch/arm/mach-ep93xx/clock.c b/arch/arm/mach-ep93xx/clock.c
new file mode 100644
index 000000000000..08ad782c1649
--- /dev/null
+++ b/arch/arm/mach-ep93xx/clock.c
@@ -0,0 +1,156 @@
+/*
+ * arch/arm/mach-ep93xx/clock.c
+ * Clock control for Cirrus EP93xx chips.
+ *
+ * Copyright (C) 2006 Lennert Buytenhek <buytenh@wantstofly.org>
+ *
+ * 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; either version 2 of the License, or (at
+ * your option) any later version.
+ */
+
+#include <linux/kernel.h>
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/string.h>
+#include <asm/div64.h>
+#include <asm/hardware.h>
+#include <asm/io.h>
+
+struct clk {
+        char            *name;
+        unsigned long   rate;
+        int             users;
+        u32             enable_reg;
+        u32             enable_mask;
+};
+
+static struct clk clk_pll1 = {
+        .name           = "pll1",
+};
+static struct clk clk_f = {
+        .name           = "fclk",
+};
+static struct clk clk_h = {
+        .name           = "hclk",
+};
+static struct clk clk_p = {
+        .name           = "pclk",
+};
+static struct clk clk_pll2 = {
+        .name           = "pll2",
+};
+static struct clk clk_usb_host = {
+        .name           = "usb_host",
+        .enable_reg     = EP93XX_SYSCON_CLOCK_CONTROL,
+        .enable_mask    = EP93XX_SYSCON_CLOCK_USH_EN,
+};
+
+
+static struct clk *clocks[] = {
+        &clk_pll1,
+        &clk_f,
+        &clk_h,
+        &clk_p,
+        &clk_pll2,
+        &clk_usb_host,
+};
+
+struct clk *clk_get(struct device *dev, const char *id)
+{
+        int i;
+
+        for (i = 0; i < ARRAY_SIZE(clocks); i++) {
+                if (!strcmp(clocks[i]->name, id))
+                        return clocks[i];
+        }
+
+        return ERR_PTR(-ENOENT);
+}
+
+int clk_enable(struct clk *clk)
+{
+        if (!clk->users++ && clk->enable_reg) {
+                u32 value;
+
+                value = __raw_readl(clk->enable_reg);
+                __raw_writel(value | clk->enable_mask, clk->enable_reg);
+        }
+
+        return 0;
+}
+
+void clk_disable(struct clk *clk)
+{
+        if (!--clk->users && clk->enable_reg) {
+                u32 value;
+
+                value = __raw_readl(clk->enable_reg);
+                __raw_writel(value & ~clk->enable_mask, clk->enable_reg);
+        }
+}
+
+unsigned long clk_get_rate(struct clk *clk)
+{
+        return clk->rate;
+}
+
+void clk_put(struct clk *clk)
+{
+}
+
+
+
+static char fclk_divisors[] = { 1, 2, 4, 8, 16, 1, 1, 1 };
+static char hclk_divisors[] = { 1, 2, 4, 5, 6, 8, 16, 32 };
+static char pclk_divisors[] = { 1, 2, 4, 8 };
+
+/*
+ * PLL rate = 14.7456 MHz * (X1FBD + 1) * (X2FBD + 1) / (X2IPD + 1) / 2^PS
+ */
+static unsigned long calc_pll_rate(u32 config_word)
+{
+        unsigned long long rate;
+        int i;
+
+        rate = 14745600;
+        rate *= ((config_word >> 11) & 0x1f) + 1;               /* X1FBD */
+        rate *= ((config_word >> 5) & 0x3f) + 1;                /* X2FBD */
+        do_div(rate, (config_word & 0x1f) + 1);                 /* X2IPD */
+        for (i = 0; i < ((config_word >> 16) & 3); i++)         /* PS */
+                rate >>= 1;
+
+        return (unsigned long)rate;
+}
+
+void ep93xx_clock_init(void)
+{
+        u32 value;
+
+        value = __raw_readl(EP93XX_SYSCON_CLOCK_SET1);
+        if (!(value & 0x00800000)) {                    /* PLL1 bypassed?  */
+                clk_pll1.rate = 14745600;
+        } else {
+                clk_pll1.rate = calc_pll_rate(value);
+        }
+        clk_f.rate = clk_pll1.rate / fclk_divisors[(value >> 25) & 0x7];
+        clk_h.rate = clk_pll1.rate / hclk_divisors[(value >> 20) & 0x7];
+        clk_p.rate = clk_h.rate / pclk_divisors[(value >> 18) & 0x3];
+
+        value = __raw_readl(EP93XX_SYSCON_CLOCK_SET2);
+        if (!(value & 0x00080000)) {                    /* PLL2 bypassed?  */
+                clk_pll2.rate = 14745600;
+        } else if (value & 0x00040000) {                /* PLL2 enabled?  */
+                clk_pll2.rate = calc_pll_rate(value);
+        } else {
+                clk_pll2.rate = 0;
+        }
+        clk_usb_host.rate = clk_pll2.rate / (((value >> 28) & 0xf) + 1);
+
+        printk(KERN_INFO "ep93xx: PLL1 running at %ld MHz, PLL2 at %ld MHz\n",
+                clk_pll1.rate / 1000000, clk_pll2.rate / 1000000);
+        printk(KERN_INFO "ep93xx: FCLK %ld MHz, HCLK %ld MHz, PCLK %ld MHz\n",
+                clk_f.rate / 1000000, clk_h.rate / 1000000,
+                clk_p.rate / 1000000);
+}
diff --git a/arch/arm/mach-ep93xx/core.c b/arch/arm/mach-ep93xx/core.c
index bf6bd71bdd08..6fd6aa74a1ff 100644
--- a/arch/arm/mach-ep93xx/core.c
+++ b/arch/arm/mach-ep93xx/core.c
@@ -437,6 +437,8 @@ void __init ep93xx_init_devices(void)
 {
         unsigned int v;
 
+        ep93xx_clock_init();
+
         /*
          * Disallow access to MaverickCrunch initially.
          */