clk: Provide OF helper to mark clocks as CRITICAL

This call matches clocks which have been marked as critical in DT
and sets the appropriate flag.  These flags can then be used to
mark the clock core flags appropriately prior to registration.

Legacy bindings requiring this feature must add the clock-critical
property to their binding descriptions, as it is not a part of
common-clock binding.

Cc: devicetree@vger.kernel.org
Signed-off-by: Lee Jones <lee.jones@linaro.org>
Reviewed-by: Stephen Boyd <sboyd@codeaurora.org>
Signed-off-by: Michael Turquette <mturquette@baylibre.com>
Link: lkml.kernel.org/r/1455225554-13267-4-git-send-email-mturquette@baylibre.com

1 files changed, 35 insertions, 0 deletions

diff --git a/drivers/clk/clk.c b/drivers/clk/clk.c
index dede0ce679e4..9f77cc67cdc3 100644
--- a/drivers/clk/clk.c
+++ b/drivers/clk/clk.c
@@ -3138,6 +3138,41 @@ static int parent_ready(struct device_node *np)
 }
 
 /**
+ * of_clk_detect_critical() - set CLK_IS_CRITICAL flag from Device Tree
+ * @np: Device node pointer associated with clock provider
+ * @index: clock index
+ * @flags: pointer to clk_core->flags
+ *
+ * Detects if the clock-critical property exists and, if so, sets the
+ * corresponding CLK_IS_CRITICAL flag.
+ *
+ * Do not use this function. It exists only for legacy Device Tree
+ * bindings, such as the one-clock-per-node style that are outdated.
+ * Those bindings typically put all clock data into .dts and the Linux
+ * driver has no clock data, thus making it impossible to set this flag
+ * correctly from the driver. Only those drivers may call
+ * of_clk_detect_critical from their setup functions.
+ *
+ * Return: error code or zero on success
+ */
+int of_clk_detect_critical(struct device_node *np,
+					  int index, unsigned long *flags)
+{
+	struct property *prop;
+	const __be32 *cur;
+	uint32_t idx;
+
+	if (!np || !flags)
+		return -EINVAL;
+
+	of_property_for_each_u32(np, "clock-critical", prop, cur, idx)
+		if (index == idx)
+			*flags |= CLK_IS_CRITICAL;
+
+	return 0;
+}
+
+/**
  * of_clk_init() - Scan and init clock providers from the DT
  * @matches: array of compatible values and init functions for providers.
  *