From: Maxime Ripard <maxime.ripard@free-electrons.com>
Date: Wed, 21 Feb 2018 10:20:25 +0100
Subject: regmap: mmio: Add function to attach a clock
Git-commit: 31895662f9ba81e8ea9ef05abf8edcb29d4b9c18
Patch-mainline: v4.17-rc1
References: FATE#326289 FATE#326079 FATE#326049 FATE#322398 FATE#326166

regmap_init_mmio_clk allows to specify a clock that needs to be enabled
while accessing the registers.

However, that clock is retrieved through its clock ID, which means it will
lookup that clock based on the current device that registers the regmap,
and, in the DT case, will only look in that device OF node.

This might be problematic if the clock to enable is stored in another node.
Let's add a function that allows to attach a clock that has already been
retrieved to a regmap in order to fix this.

Signed-off-by: Maxime Ripard <maxime.ripard@free-electrons.com>
Signed-off-by: Mark Brown <broonie@kernel.org>
Acked-by: Petr Tesarik <ptesarik@suse.com>
---
 drivers/base/regmap/regmap-mmio.c |   24 ++++++++++++++++++++++++
 include/linux/regmap.h            |    3 +++
 2 files changed, 27 insertions(+)

--- a/drivers/base/regmap/regmap-mmio.c
+++ b/drivers/base/regmap/regmap-mmio.c
@@ -28,6 +28,8 @@
 struct regmap_mmio_context {
 	void __iomem *regs;
 	unsigned val_bytes;
+
+	bool attached_clk;
 	struct clk *clk;
 
 	void (*reg_write)(struct regmap_mmio_context *ctx,
@@ -363,4 +365,26 @@ struct regmap *__devm_regmap_init_mmio_c
 }
 EXPORT_SYMBOL_GPL(__devm_regmap_init_mmio_clk);
 
+int regmap_mmio_attach_clk(struct regmap *map, struct clk *clk)
+{
+	struct regmap_mmio_context *ctx = map->bus_context;
+
+	ctx->clk = clk;
+	ctx->attached_clk = true;
+
+	return clk_prepare(ctx->clk);
+}
+EXPORT_SYMBOL_GPL(regmap_mmio_attach_clk);
+
+void regmap_mmio_detach_clk(struct regmap *map)
+{
+	struct regmap_mmio_context *ctx = map->bus_context;
+
+	clk_unprepare(ctx->clk);
+
+	ctx->attached_clk = false;
+	ctx->clk = NULL;
+}
+EXPORT_SYMBOL_GPL(regmap_mmio_detach_clk);
+
 MODULE_LICENSE("GPL v2");
--- a/include/linux/regmap.h
+++ b/include/linux/regmap.h
@@ -21,6 +21,7 @@
 #include <linux/lockdep.h>
 
 struct module;
+struct clk;
 struct device;
 struct i2c_client;
 struct irq_domain;
@@ -755,6 +756,8 @@ bool regmap_ac97_default_volatile(struct
 	__regmap_lockdep_wrapper(__devm_regmap_init_ac97, #config,	\
 				ac97, config)
 
+int regmap_mmio_attach_clk(struct regmap *map, struct clk *clk);
+void regmap_mmio_detach_clk(struct regmap *map);
 void regmap_exit(struct regmap *map);
 int regmap_reinit_cache(struct regmap *map,
 			const struct regmap_config *config);