[PATCH 12/21] ARM: tegra: clock: Add shared bus clock type

Colin Cross
2011-02-13T09:43:06Z

Some clocks may have multiple downstream users that need to request a
higher clock rate. Shared bus clocks provide a unique shared_bus_user
clock to each user. The frequency of the bus is set to the highest
enabled shared_bus_user clock, with a minimum value set by the
shared bus. Drivers can use clk_enable and clk_disable to enable
or disable their requirement, and clk_set_rate to set the minimum rate.

Signed-off-by: Colin Cross <ccross@android.com>
---
arch/arm/mach-tegra/clock.h | 8 ++++
arch/arm/mach-tegra/tegra2_clocks.c | 80 +++++++++++++++++++++++++++++++++++
2 files changed, 88 insertions(+), 0 deletions(-)

diff --git a/arch/arm/mach-tegra/clock.h b/arch/arm/mach-tegra/clock.h
index dd5c029..b460f17 100644
--- a/arch/arm/mach-tegra/clock.h
+++ b/arch/arm/mach-tegra/clock.h
@@ -85,6 +85,7 @@ struct clk {
struct clk_ops *ops;
unsigned long rate;
unsigned long max_rate;
+ unsigned long min_rate;
u32 flags;
const char *name;

@@ -98,6 +99,8 @@ struct clk {
u32 reg;
u32 reg_shift;

+ struct list_head shared_bus_list;
+
union {
struct {
unsigned int clk_num;
@@ -120,6 +123,11 @@ struct clk {
struct clk *main;
struct clk *backup;
} cpu;
+ struct {
+ struct list_head node;
+ bool enabled;
+ unsigned long rate;
+ } shared_bus_user;
} u;

spinlock_t spinlock;
diff --git a/arch/arm/mach-tegra/tegra2_clocks.c b/arch/arm/mach-tegra/tegra2_clocks.c
index a1c86d8..10b9f63 100644
--- a/arch/arm/mach-tegra/tegra2_clocks.c
+++ b/arch/arm/mach-tegra/tegra2_clocks.c
@@ -1188,6 +1188,74 @@ static struct clk_ops tegra_cdev_clk_ops = {
.disable = &tegra2_cdev_clk_disable,
};

+/* shared bus ops */
+/*
+ * Some clocks may have multiple downstream users that need to request a
+ * higher clock rate. Shared bus clocks provide a unique shared_bus_user
+ * clock to each user. The frequency of the bus is set to the highest
+ * enabled shared_bus_user clock, with a minimum value set by the
+ * shared bus.
+ */
+static void tegra_clk_shared_bus_update(struct clk *bus)
+{
+ struct clk *c;
+ unsigned long rate = bus->min_rate;
+
+ list_for_each_entry(c, &bus->shared_bus_list, u.shared_bus_user.node)
+ if (c->u.shared_bus_user.enabled)
+ rate = max(c->u.shared_bus_user.rate, rate);
+
+ if (rate != clk_get_rate(bus))
+ clk_set_rate(bus, rate);
+};
+
+static void tegra_clk_shared_bus_init(struct clk *c)
+{
+ c->max_rate = c->parent->max_rate;
+ c->u.shared_bus_user.rate = c->parent->max_rate;
+ c->state = OFF;
+#ifdef CONFIG_DEBUG_FS
+ c->set = 1;
+#endif
+
+ list_add_tail(&c->u.shared_bus_user.node,
+ &c->parent->shared_bus_list);
+}
+
+static int tegra_clk_shared_bus_set_rate(struct clk *c, unsigned long rate)
+{
+ c->u.shared_bus_user.rate = rate;
+ tegra_clk_shared_bus_update(c->parent);
+ return 0;
+}
+
+static long tegra_clk_shared_bus_round_rate(struct clk *c, unsigned long rate)
+{
+ return clk_round_rate(c->parent, rate);
+}
+
+static int tegra_clk_shared_bus_enable(struct clk *c)
+{
+ c->u.shared_bus_user.enabled = true;
+ tegra_clk_shared_bus_update(c->parent);
+ return 0;
+}
+
+static void tegra_clk_shared_bus_disable(struct clk *c)
+{
+ c->u.shared_bus_user.enabled = false;
+ tegra_clk_shared_bus_update(c->parent);
+}
+
+static struct clk_ops tegra_clk_shared_bus_ops = {
+ .init = tegra_clk_shared_bus_init,
+ .enable = tegra_clk_shared_bus_enable,
+ .disable = tegra_clk_shared_bus_disable,
+ .set_rate = tegra_clk_shared_bus_set_rate,
+ .round_rate = tegra_clk_shared_bus_round_rate,
+};
+
+
/* Clock definitions */
static struct clk tegra_clk_32k = {
.name = "clk_32k",
@@ -1858,6 +1926,17 @@ static struct clk_mux_sel mux_clk_32k[] = {
}, \
}

+#define SHARED_CLK(_name, _dev, _con, _parent) \
+ { \
+ .name = _name, \
+ .lookup = { \
+ .dev_id = _dev, \
+ .con_id = _con, \
+ }, \
+ .ops = &tegra_clk_shared_bus_ops, \
+ .parent = _parent, \
+ }
+
struct clk tegra_list_clks[] = {
PERIPH_CLK("rtc", "rtc-tegra", NULL, 4, 0, 32768, mux_clk_32k, PERIPH_NO_RESET),
PERIPH_CLK("timer", "timer", NULL, 5, 0, 26000000, mux_clk_m, 0),
@@ -2001,6 +2080,7 @@ struct clk *tegra_ptr_clks[] = {
static void tegra2_init_one_clock(struct clk *c)
{
clk_init(c);
+ INIT_LIST_HEAD(&c->shared_bus_list);
if (!c->lookup.dev_id && !c->lookup.con_id)
c->lookup.con_id = c->name;
c->lookup.clk = c;
--
1.7.3.1