clk: ti: clkctrl: add new exported API for checking standby info

Standby status is provided for certain clkctrl clocks to see if the
given module has entered standby or not. This is mostly needed by
remoteproc code to see if the remoteproc has entered standby and the clock
can be turned off safely.
Signed-off-by: Tero Kristo <t-kristo@ti.com>

drivers/clk/ti/clkctrl.c

@@ -34,6 +34,9 @@
 #define OMAP4_IDLEST_MASK		(0x3 << 16)
 #define OMAP4_IDLEST_SHIFT		16
 
+#define OMAP4_STBYST_MASK		BIT(18)
+#define OMAP4_STBYST_SHIFT		18
+
 #define CLKCTRL_IDLEST_FUNCTIONAL	0x0
 #define CLKCTRL_IDLEST_INTERFACE_IDLE	0x2
 #define CLKCTRL_IDLEST_DISABLED		0x3
@@ -647,3 +650,33 @@ static void __init _ti_omap4_clkctrl_setup(struct device_node *node)
 }
 CLK_OF_DECLARE(ti_omap4_clkctrl_clock, "ti,clkctrl",
 	       _ti_omap4_clkctrl_setup);
+
+/**
+ * ti_clk_is_in_standby - Check if clkctrl clock is in standby or not
+ * @clk: clock to check standby status for
+ *
+ * Finds whether the provided clock is in standby mode or not. Returns
+ * true if the provided clock is a clkctrl type clock and it is in standby,
+ * false otherwise.
+ */
+bool ti_clk_is_in_standby(struct clk *clk)
+{
+	struct clk_hw *hw;
+	struct clk_hw_omap *hwclk;
+	u32 val;
+
+	hw = __clk_get_hw(clk);
+
+	if (!omap2_clk_is_hw_omap(hw))
+		return false;
+
+	hwclk = to_clk_hw_omap(hw);
+
+	val = ti_clk_ll_ops->clk_readl(&hwclk->enable_reg);
+
+	if (val & OMAP4_STBYST_MASK)
+		return true;
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(ti_clk_is_in_standby);

include/linux/clk/ti.h

@@ -298,6 +298,7 @@ struct ti_clk_features {
 
 void ti_clk_setup_features(struct ti_clk_features *features);
 const struct ti_clk_features *ti_clk_get_features(void);
+bool ti_clk_is_in_standby(struct clk *clk);
 int omap3_noncore_dpll_save_context(struct clk_hw *hw);
 void omap3_noncore_dpll_restore_context(struct clk_hw *hw);