clk: tegra: defer application of init table

The Tegra clock driver is initialized during the ARM machine descriptor's
.init_irq() hook. It can't be initialized earlier, since dynamic memory
usage is required. It can't be initialized later, since the .init_timer()
hook needs the clocks initialized. However, at this time, udelay()
doesn't work.

The Tegra clock initialization table may enable some PLLs. Enabling a PLL
may require usage of udelay(). Hence, this can't happen right when the
clock driver is initialized.

To solve this, separate the clock driver initialization from the clock
table processing, so they can execute at separate times.

Signed-off-by: Stephen Warren <swarren@nvidia.com>

6 files changed, 29 insertions, 2 deletions

diff --git a/arch/arm/mach-tegra/tegra.c b/arch/arm/mach-tegra/tegra.c
index 84deeab23ee7..61749e2d8111 100644
--- a/arch/arm/mach-tegra/tegra.c
+++ b/arch/arm/mach-tegra/tegra.c
@@ -36,6 +36,7 @@
 #include <linux/slab.h>
 #include <linux/sys_soc.h>
 #include <linux/usb/tegra_usb_phy.h>
+#include <linux/clk/tegra.h>
 
 #include <asm/mach-types.h>
 #include <asm/mach/arch.h>
@@ -87,6 +88,8 @@ static void __init tegra_dt_init(void)
         struct soc_device *soc_dev;
         struct device *parent = NULL;
 
+        tegra_clocks_apply_init_table();
+
         soc_dev_attr = kzalloc(sizeof(*soc_dev_attr), GFP_KERNEL);
         if (!soc_dev_attr)
                 goto out;
diff --git a/drivers/clk/tegra/clk-tegra20.c b/drivers/clk/tegra/clk-tegra20.c
index a7dc0a937361..a15fb28197b5 100644
--- a/drivers/clk/tegra/clk-tegra20.c
+++ b/drivers/clk/tegra/clk-tegra20.c
@@ -1252,6 +1252,11 @@ static __initdata struct tegra_clk_init_table init_table[] = {
         {clk_max, clk_max, 0, 0}, /* This MUST be the last entry */
 };
 
+static void __init tegra20_clock_apply_init_table(void)
+{
+        tegra_init_from_table(init_table, clks, clk_max);
+}
+
 /*
  * Some clocks may be used by different drivers depending on the board
  * configuration.  List those here to register them twice in the clock lookup
@@ -1318,7 +1323,7 @@ void __init tegra20_clock_init(struct device_node *np)
         clk_data.clk_num = ARRAY_SIZE(clks);
         of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
 
-        tegra_init_from_table(init_table, clks, clk_max);
+        tegra_clk_apply_init_table = tegra20_clock_apply_init_table;
 
         tegra_cpu_car_ops = &tegra20_cpu_car_ops;
 }
diff --git a/drivers/clk/tegra/clk-tegra30.c b/drivers/clk/tegra/clk-tegra30.c
index 181a6eef5ce8..e0ee93c2db6c 100644
--- a/drivers/clk/tegra/clk-tegra30.c
+++ b/drivers/clk/tegra/clk-tegra30.c
@@ -1916,6 +1916,11 @@ static __initdata struct tegra_clk_init_table init_table[] = {
         {clk_max, clk_max, 0, 0}, /* This MUST be the last entry. */
 };
 
+static void __init tegra30_clock_apply_init_table(void)
+{
+        tegra_init_from_table(init_table, clks, clk_max);
+}
+
 /*
  * Some clocks may be used by different drivers depending on the board
  * configuration.  List those here to register them twice in the clock lookup
@@ -1989,7 +1994,7 @@ void __init tegra30_clock_init(struct device_node *np)
         clk_data.clk_num = ARRAY_SIZE(clks);
         of_clk_add_provider(np, of_clk_src_onecell_get, &clk_data);
 
-        tegra_init_from_table(init_table, clks, clk_max);
+        tegra_clk_apply_init_table = tegra30_clock_apply_init_table;
 
         tegra_cpu_car_ops = &tegra30_cpu_car_ops;
 }
diff --git a/drivers/clk/tegra/clk.c b/drivers/clk/tegra/clk.c
index a603b9af0ad3..4a61d15425dc 100644
--- a/drivers/clk/tegra/clk.c
+++ b/drivers/clk/tegra/clk.c
@@ -83,3 +83,13 @@ void __init tegra_clocks_init(void)
 {
         of_clk_init(tegra_dt_clk_match);
 }
+
+tegra_clk_apply_init_table_func tegra_clk_apply_init_table;
+
+void __init tegra_clocks_apply_init_table(void)
+{
+        if (!tegra_clk_apply_init_table)
+                return;
+
+        tegra_clk_apply_init_table();
+}
diff --git a/drivers/clk/tegra/clk.h b/drivers/clk/tegra/clk.h
index a09d7dcaf183..3c566e2d518a 100644
--- a/drivers/clk/tegra/clk.h
+++ b/drivers/clk/tegra/clk.h
@@ -510,4 +510,7 @@ void tegra30_clock_init(struct device_node *np);
 static inline void tegra30_clock_init(struct device_node *np) {}
 #endif /* CONFIG_ARCH_TEGRA_3x_SOC */
 
+typedef void (*tegra_clk_apply_init_table_func)(void);
+extern tegra_clk_apply_init_table_func tegra_clk_apply_init_table;
+
 #endif /* TEGRA_CLK_H */
diff --git a/include/linux/clk/tegra.h b/include/linux/clk/tegra.h
index 404d6f940872..642789baec74 100644
--- a/include/linux/clk/tegra.h
+++ b/include/linux/clk/tegra.h
@@ -123,5 +123,6 @@ static inline void tegra_cpu_clock_resume(void)
 void tegra_periph_reset_deassert(struct clk *c);
 void tegra_periph_reset_assert(struct clk *c);
 void tegra_clocks_init(void);
+void tegra_clocks_apply_init_table(void);
 
 #endif /* __LINUX_CLK_TEGRA_H_ */