[PATCH v2 2/4] doc: dt: add documentation for lpc1850-cgu clk driver
Michael Turquette
mturquette at linaro.org
Tue May 12 15:12:02 PDT 2015
Quoting Joachim Eastwood (2015-04-27 14:38:11)
> Add DT binding documentation for lpc1850-cgu driver.
>
> Signed-off-by: Joachim Eastwood <manabian at gmail.com>
> ---
> .../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 at 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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