clk: vexpress: Add separate SP810 driver

Factor out the SP810 clocking code into a separate driver,
selecting better (faster) parent at clk_prepare() time.
This is to avoid problems with clocking infrastructure
initialisation order, in particular to avoid dependency
of fixed clock being initialized before SP810. It also
makes vexpress platform OF-based clock initialisation code
unnecessary.

Signed-off-by: Pawel Moll <pawel.moll@arm.com>
Tested-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Mike Turquette <mturquette@linaro.org>
[mturquette@linaro.org: add .unprepare, FIXME comment, cleaned up code]

diff --git a/arch/arm/mach-vexpress/v2m.c b/arch/arm/mach-vexpress/v2m.c
index 915683c..c5e20b5 100644 (file)
--- a/arch/arm/mach-vexpress/v2m.c
+++ b/arch/arm/mach-vexpress/v2m.c
@@ -21,6 +21,8 @@
 #include <linux/regulator/fixed.h>
 #include <linux/regulator/machine.h>
 #include <linux/vexpress.h>
+#include <linux/clk-provider.h>
+#include <linux/clkdev.h>
 
 #include <asm/arch_timer.h>
 #include <asm/mach-types.h>
@@ -433,7 +435,7 @@ static void __init v2m_dt_timer_init(void)
 {
        struct device_node *node = NULL;
 
-       vexpress_clk_of_init();
+       of_clk_init(NULL);
 
        do {
                node = of_find_compatible_node(node, NULL, "arm,sp804");
@@ -441,6 +443,10 @@ static void __init v2m_dt_timer_init(void)
        if (node) {
                pr_info("Using SP804 '%s' as a clock & events source\n",
                                node->full_name);
+               WARN_ON(clk_register_clkdev(of_clk_get_by_name(node,
+                               "timclken1"), "v2m-timer0", "sp804"));
+               WARN_ON(clk_register_clkdev(of_clk_get_by_name(node,
+                               "timclken2"), "v2m-timer1", "sp804"));
                v2m_sp804_init(of_iomap(node, 0),
                                irq_of_parse_and_map(node, 0));
        }

diff --git a/drivers/clk/versatile/Makefile b/drivers/clk/versatile/Makefile
index ec3b88f..c16ca78 100644 (file)
--- a/drivers/clk/versatile/Makefile
+++ b/drivers/clk/versatile/Makefile
@@ -3,5 +3,5 @@ obj-$(CONFIG_ICST)              += clk-icst.o
 obj-$(CONFIG_ARCH_INTEGRATOR)  += clk-integrator.o
 obj-$(CONFIG_INTEGRATOR_IMPD1) += clk-impd1.o
 obj-$(CONFIG_ARCH_REALVIEW)    += clk-realview.o
-obj-$(CONFIG_ARCH_VEXPRESS)    += clk-vexpress.o
+obj-$(CONFIG_ARCH_VEXPRESS)    += clk-vexpress.o clk-sp810.o
 obj-$(CONFIG_VEXPRESS_CONFIG)  += clk-vexpress-osc.o

diff --git a/drivers/clk/versatile/clk-sp810.c b/drivers/clk/versatile/clk-sp810.c
new file mode 100644 (file)
index 0000000..bf9b15a
--- /dev/null
+++ b/drivers/clk/versatile/clk-sp810.c
@@ -0,0 +1,188 @@
+/*
+ * 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.
+ *
+ * Copyright (C) 2013 ARM Limited
+ */
+
+#include <linux/amba/sp810.h>
+#include <linux/clkdev.h>
+#include <linux/clk-provider.h>
+#include <linux/err.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+
+#define to_clk_sp810_timerclken(_hw) \
+               container_of(_hw, struct clk_sp810_timerclken, hw)
+
+struct clk_sp810;
+
+struct clk_sp810_timerclken {
+       struct clk_hw hw;
+       struct clk *clk;
+       struct clk_sp810 *sp810;
+       int channel;
+};
+
+struct clk_sp810 {
+       struct device_node *node;
+       int refclk_index, timclk_index;
+       void __iomem *base;
+       spinlock_t lock;
+       struct clk_sp810_timerclken timerclken[4];
+       struct clk *refclk;
+       struct clk *timclk;
+};
+
+static u8 clk_sp810_timerclken_get_parent(struct clk_hw *hw)
+{
+       struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+       u32 val = readl(timerclken->sp810->base + SCCTRL);
+
+       return !!(val & (1 << SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel)));
+}
+
+static int clk_sp810_timerclken_set_parent(struct clk_hw *hw, u8 index)
+{
+       struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+       struct clk_sp810 *sp810 = timerclken->sp810;
+       u32 val, shift = SCCTRL_TIMERENnSEL_SHIFT(timerclken->channel);
+       unsigned long flags = 0;
+
+       if (WARN_ON(index > 1))
+               return -EINVAL;
+
+       spin_lock_irqsave(&sp810->lock, flags);
+
+       val = readl(sp810->base + SCCTRL);
+       val &= ~(1 << shift);
+       val |= index << shift;
+       writel(val, sp810->base + SCCTRL);
+
+       spin_unlock_irqrestore(&sp810->lock, flags);
+
+       return 0;
+}
+
+/*
+ * FIXME - setting the parent every time .prepare is invoked is inefficient.
+ * This is better handled by a dedicated clock tree configuration mechanism at
+ * init-time.  Revisit this later when such a mechanism exists
+ */
+static int clk_sp810_timerclken_prepare(struct clk_hw *hw)
+{
+       struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+       struct clk_sp810 *sp810 = timerclken->sp810;
+       struct clk *old_parent = __clk_get_parent(hw->clk);
+       struct clk *new_parent;
+
+       if (!sp810->refclk)
+               sp810->refclk = of_clk_get(sp810->node, sp810->refclk_index);
+
+       if (!sp810->timclk)
+               sp810->timclk = of_clk_get(sp810->node, sp810->timclk_index);
+
+       if (WARN_ON(IS_ERR(sp810->refclk) || IS_ERR(sp810->timclk)))
+               return -ENOENT;
+
+       /* Select fastest parent */
+       if (clk_get_rate(sp810->refclk) > clk_get_rate(sp810->timclk))
+               new_parent = sp810->refclk;
+       else
+               new_parent = sp810->timclk;
+
+       /* Switch the parent if necessary */
+       if (old_parent != new_parent) {
+               clk_prepare(new_parent);
+               clk_set_parent(hw->clk, new_parent);
+               clk_unprepare(old_parent);
+       }
+
+       return 0;
+}
+
+static void clk_sp810_timerclken_unprepare(struct clk_hw *hw)
+{
+       struct clk_sp810_timerclken *timerclken = to_clk_sp810_timerclken(hw);
+       struct clk_sp810 *sp810 = timerclken->sp810;
+
+       clk_put(sp810->timclk);
+       clk_put(sp810->refclk);
+}
+
+static const struct clk_ops clk_sp810_timerclken_ops = {
+       .prepare = clk_sp810_timerclken_prepare,
+       .unprepare = clk_sp810_timerclken_unprepare,
+       .get_parent = clk_sp810_timerclken_get_parent,
+       .set_parent = clk_sp810_timerclken_set_parent,
+};
+
+struct clk *clk_sp810_timerclken_of_get(struct of_phandle_args *clkspec,
+               void *data)
+{
+       struct clk_sp810 *sp810 = data;
+
+       if (WARN_ON(clkspec->args_count != 1 || clkspec->args[0] >
+                       ARRAY_SIZE(sp810->timerclken)))
+               return NULL;
+
+       return sp810->timerclken[clkspec->args[0]].clk;
+}
+
+void __init clk_sp810_of_setup(struct device_node *node)
+{
+       struct clk_sp810 *sp810 = kzalloc(sizeof(*sp810), GFP_KERNEL);
+       const char *parent_names[2];
+       char name[12];
+       struct clk_init_data init;
+       int i;
+
+       if (!sp810) {
+               pr_err("Failed to allocate memory for SP810!\n");
+               return;
+       }
+
+       sp810->refclk_index = of_property_match_string(node, "clock-names",
+                       "refclk");
+       parent_names[0] = of_clk_get_parent_name(node, sp810->refclk_index);
+
+       sp810->timclk_index = of_property_match_string(node, "clock-names",
+                       "timclk");
+       parent_names[1] = of_clk_get_parent_name(node, sp810->timclk_index);
+
+       if (parent_names[0] <= 0 || parent_names[1] <= 0) {
+               pr_warn("Failed to obtain parent clocks for SP810!\n");
+               return;
+       }
+
+       sp810->node = node;
+       sp810->base = of_iomap(node, 0);
+       spin_lock_init(&sp810->lock);
+
+       init.name = name;
+       init.ops = &clk_sp810_timerclken_ops;
+       init.flags = CLK_IS_BASIC;
+       init.parent_names = parent_names;
+       init.num_parents = ARRAY_SIZE(parent_names);
+
+       for (i = 0; i < ARRAY_SIZE(sp810->timerclken); i++) {
+               snprintf(name, ARRAY_SIZE(name), "timerclken%d", i);
+
+               sp810->timerclken[i].sp810 = sp810;
+               sp810->timerclken[i].channel = i;
+               sp810->timerclken[i].hw.init = &init;
+
+               sp810->timerclken[i].clk = clk_register(NULL,
+                               &sp810->timerclken[i].hw);
+               WARN_ON(IS_ERR(sp810->timerclken[i].clk));
+       }
+
+       of_clk_add_provider(node, clk_sp810_timerclken_of_get, sp810);
+}
+CLK_OF_DECLARE(sp810, "arm,sp810", clk_sp810_of_setup);

diff --git a/drivers/clk/versatile/clk-vexpress.c b/drivers/clk/versatile/clk-vexpress.c
index 82b45aa..a4a728d 100644 (file)
--- a/drivers/clk/versatile/clk-vexpress.c
+++ b/drivers/clk/versatile/clk-vexpress.c
@@ -15,8 +15,6 @@
 #include <linux/clkdev.h>
 #include <linux/clk-provider.h>
 #include <linux/err.h>
-#include <linux/of.h>
-#include <linux/of_address.h>
 #include <linux/vexpress.h>
 
 static struct clk *vexpress_sp810_timerclken[4];
@@ -86,50 +84,3 @@ void __init vexpress_clk_init(void __iomem *sp810_base)
        WARN_ON(clk_register_clkdev(vexpress_sp810_timerclken[1],
                                "v2m-timer1", "sp804"));
 }
-
-#if defined(CONFIG_OF)
-
-struct clk *vexpress_sp810_of_get(struct of_phandle_args *clkspec, void *data)
-{
-       if (WARN_ON(clkspec->args_count != 1 || clkspec->args[0] >
-                       ARRAY_SIZE(vexpress_sp810_timerclken)))
-               return NULL;
-
-       return vexpress_sp810_timerclken[clkspec->args[0]];
-}
-
-void __init vexpress_clk_of_init(void)
-{
-       struct device_node *node;
-       struct clk *clk;
-       struct clk *refclk, *timclk;
-
-       of_clk_init(NULL);
-
-       node = of_find_compatible_node(NULL, NULL, "arm,sp810");
-       vexpress_sp810_init(of_iomap(node, 0));
-       of_clk_add_provider(node, vexpress_sp810_of_get, NULL);
-
-       /* Select "better" (faster) parent for SP804 timers */
-       refclk = of_clk_get_by_name(node, "refclk");
-       timclk = of_clk_get_by_name(node, "timclk");
-       if (!WARN_ON(IS_ERR(refclk) || IS_ERR(timclk))) {
-               int i = 0;
-
-               if (clk_get_rate(refclk) > clk_get_rate(timclk))
-                       clk = refclk;
-               else
-                       clk = timclk;
-
-               for (i = 0; i < ARRAY_SIZE(vexpress_sp810_timerclken); i++)
-                       WARN_ON(clk_set_parent(vexpress_sp810_timerclken[i],
-                                       clk));
-       }
-
-       WARN_ON(clk_register_clkdev(vexpress_sp810_timerclken[0],
-                               "v2m-timer0", "sp804"));
-       WARN_ON(clk_register_clkdev(vexpress_sp810_timerclken[1],
-                               "v2m-timer1", "sp804"));
-}
-
-#endif