[U-Boot] [PATCH 1/2] ARM: tegra: Define Tegra20 CAR binding

Simon Glass sjg at chromium.org
Wed Jan 25 21:14:13 CET 2012


Hi Stephen,

On Wed, Jan 25, 2012 at 11:57 AM, Stephen Warren <swarren at nvidia.com> wrote:
> Document a binding for the Tegra20 CAR (Clock And Reset) Controller,
> add it to tegra20.dtsi, and configure it for the board in tegra-
> seaboard.dts.
>
> Signed-off-by: Stephen Warren <swarren at nvidia.com>
> ---
> v2:
> * Remove clock-names, clock-output-names properties; Tegra will solely
>  use integer IDs for clocks in DT.
> * Fixed typo in compatible flag
> * Resolve FIXME re: multiple clocks with the same "reset ID"; give each
>  unique clock an ID, and ignore the reset bits, since this is purely a
>  clock binding. Code (e.g. U-Boot) that wants to use this to determine
>  CAR reset bit numbers would need a table to convert from the clock IDs
>  in this binding to the related reset bit number, if any. In general, I
>  think that's true, and the U-Boot code that handles "peripheral IDs"
>  should be reworked to handle "clocks", the peripheral clocks being a
>  subset of all clocks.

The clock enable and reset enable bits use the same numbering. I think
you have invented a third which is an arbitrary number which doesn't
correspond to anything in hardware. That makes sense for pin mux
function perhaps, since the indirection provides a useful concept of
function number, but here I can't see the benefit.

> * Define clock IDs for all the non-peripheral clocks too; inputs, PLLs,
>  etc.
> * Separate tegra-seaboard.dts usage example into a separate patch.
>
> This patch semantically relies on Grant Likely's common clock binding patch
> series. Once that's finalized, this patch could be checked into the kernel
> provided there are no relevant changes to Grant's patches. I believe that
> Simon Glass wants to start using this within U-Boot ASAP though.

As I may have said I am really not keen on the idea of having a table
just to use it in U-Boot.

> ---
>  .../bindings/clock/nvidia,tegra20-car.txt          |  164 ++++++++++++++++++++
>  arch/arm/boot/dts/tegra20.dtsi                     |    6 +
>  2 files changed, 170 insertions(+), 0 deletions(-)
>  create mode 100644 Documentation/devicetree/bindings/clock/nvidia,tegra20-car.txt
>
> diff --git a/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.txt b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.txt
> new file mode 100644
> index 0000000..acce2d9
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/nvidia,tegra20-car.txt
> @@ -0,0 +1,164 @@
> +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,<chip>-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. Later, subsequent IDs will be assigned to all other clocks the
> +  CAR controls; mainly the PLLs.

Are you sure? The ordering doesn't seem to fit with U-Boot's enum
periph_id in arch/arm/include/asm/arch-tegra2/clock.h. That file
follows along with the hardware.

> +
> +    0  osc
> +    1  clk_32k         a/k/a clk_s
> +    2  clk_m
> +    3  sclk
> +    4  cclk
> +    5  hclk
> +    6  pclk
> +    7  blink
> +    8  pll_a
> +    9  pll_a_out0
> +    10 pll_c
> +    11 pll_c_out1
> +    12 pll_d
> +    13 pll_e
> +    14 pll_m
> +    15 pll_m_out1
> +    16 pll_p
> +    17 pll_p_out1
> +    18 pll_p_out2
> +    19 pll_p_out3
> +    20 pll_p_out4
> +    21 pll_s
> +    22 pll_u
> +    23 pll_x
> +    24 audio           a/k/a audio_sync_clk
> +    25 audio_2x        a/k/a audio_2x_sync_clk
> +    26 cpu
> +    27 cop             a/k/a avp
> +    28 ac97
> +    29 rtc
> +    30 tmr
> +    31 uart1
> +    32 uart2
> +    33 gpio
> +    34 sdmmc2
> +    35 spdif_out
> +    36 spdif_in
> +    37 i2s1
> +    38 i2c1
> +    39 ndflash
> +    40 sdmmc1
> +    41 sdmmc4
> +    42 twc
> +    43 pwm
> +    44 i2s2
> +    45 epp
> +    46 vi
> +    47 vi_sensor
> +    48 2d
> +    49 usbd
> +    50 isp
> +    51 3d
> +    52 ide
> +    53 disp2
> +    54 disp1
> +    55 host1x
> +    56 vcp
> +    57 cache2
> +    58 mem
> +    59 ahbdma
> +    60 apbdma
> +    61 kbc
> +    62 stat_mon
> +    63 pmc
> +    64 fuse
> +    65 kfuse
> +    66 sbc1
> +    67 snor
> +    68 spi
> +    69 sbc2
> +    70 xio
> +    71 sbc3
> +    72 dvc
> +    73 dsi
> +    74 cve
> +    75 tvo
> +    76 mipi
> +    77 hdmi
> +    78 csi
> +    79 tvdac
> +    80 i2c2
> +    81 uart3
> +    82 emc
> +    83 usb2
> +    84 usb3
> +    85 mpe
> +    86 vde
> +    87 bsea
> +    88 bsev
> +    89 speedo
> +    90 uart4
> +    91 uart5
> +    92 i2c3
> +    93 sbc4
> +    94 sdmmc3
> +    95 pcie
> +    96 owr
> +    97 afi
> +    98 csite
> +    99 avpucq
> +    100        la
> +    101        irama
> +    102        iramb
> +    103        iramc
> +    104        iramd
> +    105        cram2
> +    106        clk_d
> +    107        sus
> +    108        cdev1
> +    109        cdev2
> +
> +Example:
> +
> +clocks {
> +       #address-cells = <1>;
> +       #size-cells = <0>;
> +
> +       clk_32k: clock at 0 {
> +               compatible = "fixed-clock";
> +               reg = <0>;
> +               #clock-cells = <0>;
> +               clock-frequency = <32768>;
> +       };
> +
> +       osc: clock at 1 {
> +               compatible = "fixed-clock";
> +               reg = <1>;
> +               #clock-cells = <0>;
> +               clock-frequency = <12000000>;
> +       };
> +};
> +
> +tegra_car: clock at 60006000 {
> +       compatible = "nvidia,tegra20-car";
> +       reg = <0x60006000 1000>;
> +       clocks = <&clk_32k> <&osc>;
> +       clock-names = "32k_in", "osc";
> +       #clock-cells = <1>;
> +};
> +
> +usb at c5004000 {
> +       ...
> +       clocks = <&tegra_car 58>; /* usb2 */
> +};
> diff --git a/arch/arm/boot/dts/tegra20.dtsi b/arch/arm/boot/dts/tegra20.dtsi
> index 3da7afd..8208660 100644
> --- a/arch/arm/boot/dts/tegra20.dtsi
> +++ b/arch/arm/boot/dts/tegra20.dtsi
> @@ -4,6 +4,12 @@
>        compatible = "nvidia,tegra20";
>        interrupt-parent = <&intc>;
>
> +       tegra_car: clock at 60006000 {
> +               compatible = "nvidia,tegra20-car";
> +               reg = <0x60006000 1000>;
> +               #clock-cells = <1>;
> +       };
> +
>        intc: interrupt-controller at 50041000 {
>                compatible = "arm,cortex-a9-gic";
>                interrupt-controller;
> --
> 1.7.0.4
>

Regards,
Simon


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