nvmem: core: remove regmap dependency

nvmem uses regmap_raw_read/write apis to read/write data from providers,
regmap raw apis stopped working with recent kernels which removed raw
accessors on mmio bus. This resulted in broken nvmem for providers
which are based on regmap mmio bus. This issue can be fixed temporarly
by moving to other regmap apis, but we might hit same issue in future.
Moving to interfaces based on read/write callbacks from providers would
be more robust.

This patch removes regmap dependency from nvmem and introduces
read/write callbacks from the providers.

Without this patch nvmem providers like qfprom based on regmap mmio
bus would not work.

Reported-by: Rajendra Nayak <rjendra@qti.qualcomm.com>
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/linux/nvmem-provider.h b/include/linux/nvmem-provider.h
index a4fcc90..cd93416 100644
--- a/include/linux/nvmem-provider.h
+++ b/include/linux/nvmem-provider.h
@@ -14,6 +14,10 @@
 
 struct nvmem_device;
 struct nvmem_cell_info;
+typedef int (*nvmem_reg_read_t)(void *priv, unsigned int offset,
+				void *val, size_t bytes);
+typedef int (*nvmem_reg_write_t)(void *priv, unsigned int offset,
+				 void *val, size_t bytes);
 
 struct nvmem_config {
 	struct device		*dev;
@@ -24,6 +28,12 @@
 	int			ncells;
 	bool			read_only;
 	bool			root_only;
+	nvmem_reg_read_t	reg_read;
+	nvmem_reg_write_t	reg_write;
+	int	size;
+	int	word_size;
+	int	stride;
+	void	*priv;
 	/* To be only used by old driver/misc/eeprom drivers */
 	bool			compat;
 	struct device		*base_dev;