Re: [PATCH v2 2/4] doc: dt: add documentation for lpc1850-cgu clk driver

[Michael Turquette <mturquette-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org>]

Quoting Joachim Eastwood (2015-04-27 14:38:11)
> Add DT binding documentation for lpc1850-cgu driver.
> 
> Signed-off-by: Joachim Eastwood <manabian-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
> ---
>  .../devicetree/bindings/clock/lpc1850-cgu.txt      | 138 +++++++++++++++++++++
>  1 file changed, 138 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/clock/lpc1850-cgu.txt
> 
> diff --git a/Documentation/devicetree/bindings/clock/lpc1850-cgu.txt b/Documentation/devicetree/bindings/clock/lpc1850-cgu.txt
> new file mode 100644
> index 000000000000..0b278ca6aee7
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/lpc1850-cgu.txt
> @@ -0,0 +1,138 @@
> +* NXP LPC1850 Clock Generation Unit (CGU)
> +
> +The CGU generates multiple independent clocks for the core and the
> +peripheral blocks of the LPC18xx. Each independent clock is called
> +a base clock and itself is one of the inputs to the two Clock
> +Control Units (CCUs) which control the branch clocks to the
> +individual peripherals.
> +
> +The CGU selects the inputs to the clock generators from multiple
> +clock sources, controls the clock generation, and routes the outputs
> +of the clock generators through the clock source bus to the output
> +stages. Each output stage provides an independent clock source and
> +corresponds to one of the base clocks for the LPC18xx.
> +
> + - Above text taken from NXP LPC1850 User Manual.
> +
> +
> +This binding uses the common clock binding:
> +    Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible:
> +       Should be "nxp,lpc1850-cgu"
> +- reg:
> +       Shall define the base and range of the address space
> +       containing clock control registers
> +- #clock-cells:
> +       Shall have value <1>.  The permitted clock-specifier values
> +       are the base clock numbers defined below.
> +- clocks:
> +       Shall contain a list of phandles for the external input
> +       sources to the CGU. The list shall be in the following
> +       order: xtal, 32khz, enet_rx_clk, enet_tx_clk, gp_clkin.
> +- clock-indices:
> +       Shall be an ordered list of numbers defining the base clock
> +       number provided by the CGU.
> +- clock-output-names:
> +       Shall be an ordered list of strings defining the names of
> +       the clocks provided by the CGU.
> +
> +Which base clocks that are available on the CGU depends on the
> +specific LPC part. Base cloks are numbered from 0 to 27.

s/cloks/clocks/

> +
> +Number:                Name:                   Description:
> + 0             BASE_SAFE_CLK           Base safe clock (always on) for WWDT
> + 1             BASE_USB0_CLK           Base clock for USB0
> + 2             BASE_PERIPH_CLK         Base clock for Cortex-M0SUB subsystem,
> +                                       SPI, and SGPIO
> + 3             BASE_USB1_CLK           Base clock for USB1
> + 4             BASE_CPU_CLK            System base clock for ARM Cortex-M core
> +                                       and APB peripheral blocks #0 and #2
> + 5             BASE_SPIFI_CLK          Base clock for SPIFI
> + 6             BASE_SPI_CLK            Base clock for SPI
> + 7             BASE_PHY_RX_CLK         Base clock for Ethernet PHY Receive clock
> + 8             BASE_PHY_TX_CLK         Base clock for Ethernet PHY Transmit clock
> + 9             BASE_APB1_CLK           Base clock for APB peripheral block # 1
> +10             BASE_APB3_CLK           Base clock for APB peripheral block # 3
> +11             BASE_LCD_CLK            Base clock for LCD
> +12             BASE_ADCHS_CLK          Base clock for ADCHS
> +13             BASE_SDIO_CLK           Base clock for SD/MMC
> +14             BASE_SSP0_CLK           Base clock for SSP0
> +15             BASE_SSP1_CLK           Base clock for SSP1
> +16             BASE_UART0_CLK          Base clock for UART0
> +17             BASE_UART1_CLK          Base clock for UART1
> +18             BASE_UART2_CLK          Base clock for UART2
> +19             BASE_UART3_CLK          Base clock for UART3
> +20             BASE_OUT_CLK            Base clock for CLKOUT pin
> +24-21          -                       Reserved
> +25             BASE_AUDIO_CLK          Base clock for audio system (I2S)
> +26             BASE_CGU_OUT0_CLK       Base clock for CGU_OUT0 clock output
> +27             BASE_CGU_OUT1_CLK       Base clock for CGU_OUT1 clock output
> +
> +BASE_PERIPH_CLK and BASE_SPI_CLK is only available on LPC43xx.
> +BASE_ADCHS_CLK is only available on LPC4370.
> +
> +
> +Example board file:
> +
> +/ {
> +       clocks {
> +               xtal: xtal {
> +                       compatible = "fixed-clock";
> +                       #clock-cells = <0>;
> +                       clock-frequency = <12000000>;
> +               };
> +
> +               xtal32: xtal32 {
> +                       compatible = "fixed-clock";
> +                       #clock-cells = <0>;
> +                       clock-frequency = <32768>;
> +               };
> +
> +               enet_rx_clk: enet_rx_clk {
> +                       compatible = "fixed-clock";
> +                       #clock-cells = <0>;
> +                       clock-frequency = <0>;
> +                       clock-output-names = "enet_rx_clk";
> +               };
> +
> +               enet_tx_clk: enet_tx_clk {
> +                       compatible = "fixed-clock";
> +                       #clock-cells = <0>;
> +                       clock-frequency = <0>;
> +                       clock-output-names = "enet_tx_clk";
> +               };
> +
> +               gp_clkin: gp_clkin {
> +                       compatible = "fixed-clock";
> +                       #clock-cells = <0>;
> +                       clock-frequency = <0>;
> +                       clock-output-names = "gp_clkin";
> +               };
> +       };
> +
> +       soc {
> +               cgu: cgu@40050000 {
> +                       compatible = "nxp,lpc1850-cgu";
> +                       reg = <0x40050000 0x1000>;
> +                       #clock-cells = <1>;
> +                       clocks = <&xtal>, <&creg_clk 1>, <&enet_rx_clk>, <&enet_tx_clk>, <&gp_clkin>;
> +                       clock-indices =  <0>,  <1>,  <2>,  <3>,  <4>,  <5>,  <6>,  <7>,
> +                                        <8>,  <9>, <10>, <11>, <12>, <13>, <14>, <15>,
> +                                       <16>, <17>, <18>, <19>, <20>, <25>, <26>, <27>;
> +                       clock-output-names = "base_safe_clk",    "base_usb0_clk",
> +                                            "base_periph_clk",  "base_usb1_clk",
> +                                            "base_cpu_clk",     "base_spifi_clk",
> +                                            "base_spi_clk",     "base_phy_rx_clk",
> +                                            "base_phy_tx_clk",  "base_apb1_clk",
> +                                            "base_apb3_clk",    "base_lcd_clk",
> +                                            "base_adchs_clk",   "base_sdio_clk",
> +                                            "base_ssp0_clk",    "base_ssp1_clk",
> +                                            "base_uart0_clk",   "base_uart1_clk",
> +                                            "base_uart2_clk",   "base_uart3_clk",
> +                                            "base_out_clk",     "base_audio_clk",
> +                                            "base_cgu_out0_clk","base_cgu_out1_clk";

Why do you need to use clock-indices?

Why do you need to use clock-output-names? If all of your clock
consumers have nodes in DT then you can skip this and name them on the
consuming side. See a further explanation here:
http://lkml.kernel.org/r/<20150416192014.19585.9663@quantum>

Also note that providing a clock consumer node in the examples section
of the binding is helpful when reviewing.

Regards,
Mike

> +               };
> +       };
> +};
> -- 
> 1.8.0
> 
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