tegra: fdt: Add clock bindings

This adds a basic binding for the oscillator and peripheral clocks. The
second cell is the clock number, defined as the bit number within the clock
enable register if the peripheral clock.

This uses the RFC clock bindings from Grant Likely so may change later:

https://lkml.org/lkml/2011/12/12/498

It is taken from Stephen Warren's patch here:

http://patchwork.ozlabs.org/patch/141359/

Signed-off-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Tom Warren <twarren@nvidia.com>

arch/arm/dts/tegra20.dtsi

@@ -4,6 +4,22 @@
 	compatible = "nvidia,tegra20";
 	interrupt-parent = <&intc>;
 
+	tegra_car: clock@60006000 {
+		compatible = "nvidia,tegra20-car";
+		reg = <0x60006000 0x1000>;
+		#clock-cells = <1>;
+	};
+
+	clocks {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		osc: clock {
+			compatible = "fixed-clock";
+			#clock-cells = <0>;
+		};
+	};
+
 	intc: interrupt-controller@50041000 {
 		compatible = "nvidia,tegra20-gic";
 		interrupt-controller;

doc/device-tree-bindings/clock/nvidia,tegra20-car.txt

@@ -0,0 +1,207 @@
+NVIDIA Tegra20 Clock And Reset Controller
+
+This binding uses the common clock binding:
+Documentation/devicetree/bindings/clock/clock-bindings.txt
+
+The CAR (Clock And Reset) Controller on Tegra is the HW module responsible
+for muxing and gating Tegra's clocks, and setting their rates.
+
+Required properties :
+- compatible : Should be "nvidia,tegra20-car"
+- reg : Should contain CAR registers location and length
+- clocks : Should contain phandle and clock specifiers for two clocks:
+  the 32 KHz "32k_in", and the board-specific oscillator "osc".
+- #clock-cells : Should be 1.
+  In clock consumers, this cell represents the clock ID exposed by the CAR.
+
+  The first 96 clocks are numbered to match the bits in the CAR's CLK_OUT_ENB
+  registers. These IDs often match those in the CAR's RST_DEVICES registers,
+  but not in all cases. Some bits in CLK_OUT_ENB affect multiple clocks. In
+  this case, those clocks are assigned IDs above 95 in order to highlight
+  this issue. Implementations that interpret these clock IDs as bit values
+  within the CLK_OUT_ENB or RST_DEVICES registers should be careful to
+  explicitly handle these special cases.
+
+  The balance of the clocks controlled by the CAR are assigned IDs of 96 and
+  above.
+
+  0	cpu
+  1	unassigned
+  2	unassigned
+  3	ac97
+  4	rtc
+  5	tmr
+  6	uart1
+  7	unassigned	(register bit affects uart2 and vfir)
+  8	gpio
+  9	sdmmc2
+  10	unassigned	(register bit affects spdif_in and spdif_out)
+  11	i2s1
+  12	i2c1
+  13	ndflash
+  14	sdmmc1
+  15	sdmmc4
+  16	twc
+  17	pwm
+  18	i2s2
+  19	epp
+  20	unassigned	(register bit affects vi and vi_sensor)
+  21	2d
+  22	usbd
+  23	isp
+  24	3d
+  25	ide
+  26	disp2
+  27	disp1
+  28	host1x
+  29	vcp
+  30	unassigned
+  31	cache2
+
+  32	mem
+  33	ahbdma
+  34	apbdma
+  35	unassigned
+  36	kbc
+  37	stat_mon
+  38	pmc
+  39	fuse
+  40	kfuse
+  41	sbc1
+  42	snor
+  43	spi1
+  44	sbc2
+  45	xio
+  46	sbc3
+  47	dvc
+  48	dsi
+  49	unassigned	(register bit affects tvo and cve)
+  50	mipi
+  51	hdmi
+  52	csi
+  53	tvdac
+  54	i2c2
+  55	uart3
+  56	unassigned
+  57	emc
+  58	usb2
+  59	usb3
+  60	mpe
+  61	vde
+  62	bsea
+  63	bsev
+
+  64	speedo
+  65	uart4
+  66	uart5
+  67	i2c3
+  68	sbc4
+  69	sdmmc3
+  70	pcie
+  71	owr
+  72	afi
+  73	csite
+  74	unassigned
+  75	avpucq
+  76	la
+  77	unassigned
+  78	unassigned
+  79	unassigned
+  80	unassigned
+  81	unassigned
+  82	unassigned
+  83	unassigned
+  84	irama
+  85	iramb
+  86	iramc
+  87	iramd
+  88	cram2
+  89	audio_2x	a/k/a audio_2x_sync_clk
+  90	clk_d
+  91	unassigned
+  92	sus
+  93	cdev1
+  94	cdev2
+  95	unassigned
+
+  96	uart2
+  97	vfir
+  98	spdif_in
+  99	spdif_out
+  100	vi
+  101	vi_sensor
+  102	tvo
+  103	cve
+  104	osc
+  105	clk_32k		a/k/a clk_s
+  106	clk_m
+  107	sclk
+  108	cclk
+  109	hclk
+  110	pclk
+  111	blink
+  112	pll_a
+  113	pll_a_out0
+  114	pll_c
+  115	pll_c_out1
+  116	pll_d
+  117	pll_d_out0
+  118	pll_e
+  119	pll_m
+  120	pll_m_out1
+  121	pll_p
+  122	pll_p_out1
+  123	pll_p_out2
+  124	pll_p_out3
+  125	pll_p_out4
+  126	pll_s
+  127	pll_u
+  128	pll_x
+  129	cop		a/k/a avp
+  130	audio		a/k/a audio_sync_clk
+
+Example SoC include file:
+
+/ {
+	tegra_car: clock@60006000 {
+		compatible = "nvidia,tegra20-car";
+		reg = <0x60006000 0x1000>;
+		#clock-cells = <1>;
+	};
+
+	usb@c5004000 {
+		clocks = <&tegra_car 58>; /* usb2 */
+	};
+};
+
+Example board file:
+
+/ {
+	clocks {
+		#address-cells = <1>;
+		#size-cells = <0>;
+
+		osc: clock {
+			compatible = "fixed-clock";
+			#clock-cells = <0>;
+			clock-frequency = <12000000>;
+		};
+	};
+
+	i2c@7000d000 {
+		pmic@34 {
+			compatible = "ti,tps6586x";
+			reg = <0x34>;
+
+			clk_32k: clock {
+				compatible = "fixed-clock";
+				#clock-cells = <0>;
+				clock-frequency = <32768>;
+			};
+		};
+	};
+
+	&tegra_car {
+		clocks = <&clk_32k> <&osc>;
+	};
+};