clk: Add driver for MAX9485

This patch adds a driver for MAX9485, a programmable audio clock generator.

The device requires a 27.000 MHz clock input. It can provide a gated
buffered output of its input clock and two gated outputs of a PLL that can
generate one out of 16 discrete frequencies. There is only one PLL however,
so the two gated outputs will always have the same frequency but they can
be switched individually.

The driver for this device exposes 4 clocks in total:

- MAX9485_MCLKOUT:      A gated, buffered output of the input clock
- MAX9485_CLKOUT:       A PLL that can be configured to 16 different
			discrete frequencies
- MAX9485_CLKOUT[1,2]:  Two gated outputs for MAX9485_CLKOUT

Some PLL output frequencies can be achieved with different register
settings. The driver will select the one with lowest jitter in such cases.

Signed-off-by: Daniel Mack <[email protected]>
[[email protected]: Use local variable for val in max9485_clkout_recalc_rate()
and shorten line of max9485_of_clk_get()]
Signed-off-by: Stephen Boyd <[email protected]>

drivers/clk/Kconfig

@@ -45,6 +45,12 @@ config COMMON_CLK_MAX77686
 	  This driver supports Maxim 77620/77686/77802 crystal oscillator
 	  clock.
 
+config COMMON_CLK_MAX9485
+	tristate "Maxim 9485 Programmable Clock Generator"
+	depends on I2C
+	help
+	  This driver supports Maxim 9485 Programmable Audio Clock Generator
+
 config COMMON_CLK_RK808
 	tristate "Clock driver for RK805/RK808/RK818"
 	depends on MFD_RK808

drivers/clk/Makefile

@@ -31,6 +31,7 @@ obj-$(CONFIG_COMMON_CLK_ASPEED)		+= clk-aspeed.o
 obj-$(CONFIG_ARCH_HIGHBANK)		+= clk-highbank.o
 obj-$(CONFIG_CLK_HSDK)			+= clk-hsdk-pll.o
 obj-$(CONFIG_COMMON_CLK_MAX77686)	+= clk-max77686.o
+obj-$(CONFIG_COMMON_CLK_MAX9485)	+= clk-max9485.o
 obj-$(CONFIG_ARCH_MOXART)		+= clk-moxart.o
 obj-$(CONFIG_ARCH_NOMADIK)		+= clk-nomadik.o
 obj-$(CONFIG_ARCH_NPCM7XX)	    	+= clk-npcm7xx.o