ARM: imx: add shared gate clock support

It's quite common on i.MX that one gate bit controls the gating of
multiple clocks, i.e. this is a shared gate.  The patch adds the
function imx_clk_gate2_shared() for such case.  The clocks controlled
by the same gate bits should call this function with a pointer to a
single share count variable, so that the gate bits will only be
operated on the first enabling and the last disabling of these shared
gate clocks.

Thanks to Gerhard Sittig <gsi@denx.de> for this idea.

Signed-off-by: Shawn Guo <shawn.guo@freescale.com>
[shawn.guo: cherry-pick commit f9f28cdf2167 from upstream]

1 files changed, 11 insertions, 2 deletions

diff --git a/arch/arm/mach-imx/clk.h b/arch/arm/mach-imx/clk.h
index 048c5ad8a80b..e29f6ebe9f39 100644
--- a/arch/arm/mach-imx/clk.h
+++ b/arch/arm/mach-imx/clk.h
@@ -28,7 +28,8 @@ struct clk *imx_clk_pllv3(enum imx_pllv3_type type, const char *name,
 struct clk *clk_register_gate2(struct device *dev, const char *name,
 		const char *parent_name, unsigned long flags,
 		void __iomem *reg, u8 bit_idx,
-		u8 clk_gate_flags, spinlock_t *lock);
+		u8 clk_gate_flags, spinlock_t *lock,
+		unsigned int *share_count);
 
 struct clk * imx_obtain_fixed_clock(
 			const char *name, unsigned long rate);
@@ -37,7 +38,15 @@ static inline struct clk *imx_clk_gate2(const char *name, const char *parent,
 		void __iomem *reg, u8 shift)
 {
 	return clk_register_gate2(NULL, name, parent, CLK_SET_RATE_PARENT, reg,
-			shift, 0, &imx_ccm_lock);
+			shift, 0, &imx_ccm_lock, NULL);
+}
+
+static inline struct clk *imx_clk_gate2_shared(const char *name,
+		const char *parent, void __iomem *reg, u8 shift,
+		unsigned int *share_count)
+{
+	return clk_register_gate2(NULL, name, parent, CLK_SET_RATE_PARENT, reg,
+			shift, 0, &imx_ccm_lock, share_count);
 }
 
 struct clk *imx_clk_pfd(const char *name, const char *parent_name,