clk: gate: add CLK_GATE_ALWAYS_ON

By default gate clock could be enable and disable. but in some debug condition, must keep clock on, and never be closed. setting this flag then gate clock never be closed.

Signed-off-by Shaojie Sun <[email protected]>

---
 drivers/clk/clk-gate.c       |   24 ++++++++++++++++++++++++
 include/linux/clk-provider.h |    4 ++++
 2 files changed, 28 insertions(+)

drivers/clk/clk-gate.c +11 -0

 /**
  * DOC: basic gatable clock which can gate and ungate it's ouput

@@ -48,6 +49,9 @@ static void clk_gate_endisable(struct clk_hw *hw, int enable)
        unsigned long flags = 0;
        u32 reg;
 
+       if (!enable && (gate->flags & CLK_GATE_ALWAYS_ON))
+               return;
+
        set ^= enable;
 
        if (gate->lock)

@@ -159,5 +163,25 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
        if (IS_ERR(clk))
                kfree(gate);
 
+       if (clk_gate_flags & CLK_GATE_ALWAYS_ON) {
+               int ret;
+               if (flags & CLK_SET_PARENT_GATE)
+                       pr_debug("%s: %salways on, but need parent gate.\n",
+                                       __func__, name);
+
+               ret = clk_prepare(clk);
+               if (ret) {

drivers/clk/clk-gate.c +2 -0

+       }
+
        return clk;
 }

include/linux/clk-provider.h +0 -0

index 1ec14a7..641422c 100644

Added linaro-kernel & patches at linaro.org in cc list..

Quoted 3 lines · Shaojie Sun

By default gate clock could be enable and disable. but in some debug condition, must keep clock on, and never be closed. setting this flag then gate clock never be closed.

Consider rewriting it as:

By default gate clk can be enabled/disabled but during debugging we may want to disable clk-disabling feature.

This patch adds a flag for it..

Quoted 5 lines

Signed-off-by Shaojie Sun <[email protected]>

---
 drivers/clk/clk-gate.c       |   24 ++++++++++++++++++++++++
 include/linux/clk-provider.h |    4 ++++
 2 files changed, 28 insertions(+)

Honestly speaking, I am not sure if this patch is really required or not. And so Mike can decide on that. I will do a simple code review in that time.

drivers/clk/clk-gate.c line 18

Quoted 10 lines

drivers/clk/clk-gate.c +1 -0

index 790306e..cc2b00e 100644
@@ -15,6 +15,7 @@
 #include <linux/io.h>
 #include <linux/err.h>
 #include <linux/string.h>
+#include <linux/device.h>

why?

Quoted 24 lines

drivers/clk/clk-gate.c +11 -0

 /**
  * DOC: basic gatable clock which can gate and ungate it's ouput

@@ -48,6 +49,9 @@ static void clk_gate_endisable(struct clk_hw *hw, int enable)
        unsigned long flags = 0;
        u32 reg;
 
+       if (!enable && (gate->flags & CLK_GATE_ALWAYS_ON))
+               return;
+
        set ^= enable;
 
        if (gate->lock)

@@ -159,5 +163,25 @@ struct clk *clk_register_gate(struct device *dev, const char *name,
        if (IS_ERR(clk))
                kfree(gate);
 
+       if (clk_gate_flags & CLK_GATE_ALWAYS_ON) {
+               int ret;
+               if (flags & CLK_SET_PARENT_GATE)
+                       pr_debug("%s: %salways on, but need parent gate.\n",
+                                       __func__, name);
+
+               ret = clk_prepare(clk);
+               if (ret) {

drivers/clk/clk-gate.c struct clk *clk_register_gate(struct device *dev, const char *name, · line 183

Quoted 10 lines

drivers/clk/clk-gate.c +10 -0

+                       pr_debug("%s: %s could not be prepared.\n",
+                                       __func__, name);
+                       return clk;
+               }
+               ret = clk_enable(clk);
+               if (ret) {
+                       pr_debug("%s: %s could not be enabled.\n",
+                                       __func__, name);
+                       clk_unprepare(clk);
+               }

Call clk_prepare_enable instead.

Quoted 9 lines

drivers/clk/clk-gate.c +2 -0

+       }
+
        return clk;
 }

include/linux/clk-provider.h +0 -0

index 1ec14a7..641422c 100644

include/linux/clk-provider.h void of_fixed_clk_setup(struct device_node *np); · line 219

Quoted 6 lines

include/linux/clk-provider.h +3 -0

@@ -214,6 +214,9 @@ void of_fixed_clk_setup(struct device_node *np);
  *   of this register, and mask of gate bits are in higher 16-bit of this
  *   register.  While setting the gate bits, higher 16-bit should also be
  *   updated to indicate changing gate bits.
+ * CLK_GATE_ALWAYS_ON - by default this clock could be enable and disable. but
+ *   in some debug condition, must keep this clock on, and never be closed.
+ *   setting this flag then this clock never be closed.

Copy some part from the commit log I just suggested..

If this flag is only for debugging we may name it that way.
Maybe: CLK_GATE_DBG_ALWAYS_ON ??