Re: [PATCH v2 03/14] DEVICETREE: Add PIC32 clock binding documentation

From: Rob Herring
Date: Fri Dec 18 2015 - 10:44:55 EST

On Mon, Dec 14, 2015 at 03:42:05PM -0700, Joshua Henderson wrote:
> From: Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>
>
> Document the devicetree bindings for the clock driver found on Microchip
> PIC32 class devices.
>
> Signed-off-by: Purna Chandra Mandal <purna.mandal@xxxxxxxxxxxxx>
> Signed-off-by: Joshua Henderson <joshua.henderson@xxxxxxxxxxxxx>
> Cc: Ralf Baechle <ralf@xxxxxxxxxxxxxx>

A couple of nits on the example, otherwise:

Acked-by: Rob Herring <robh@xxxxxxxxxx>

> ---
> .../devicetree/bindings/clock/microchip,pic32.txt | 256 ++++++++++++++++++++
> 1 file changed, 256 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/clock/microchip,pic32.txt
>
> diff --git a/Documentation/devicetree/bindings/clock/microchip,pic32.txt b/Documentation/devicetree/bindings/clock/microchip,pic32.txt
> new file mode 100644
> index 0000000..f50c653
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/clock/microchip,pic32.txt
> @@ -0,0 +1,256 @@
> +Binding for a Clock hardware block found on
> +certain Microchip PIC32 MCU devices.
> +
> +Microchip SoC clocks-node consists of few oscillators, PLL, multiplexer
> +and few divider nodes.
> +
> +We will find only the base address of the clock tree, this base
> +address is common for some of the subnodes, not all. If no address is
> +specified for any of subnode base address of the clock tree will be
> +treated as its base. Each of subnodes follow the same common clock
> +binding with some additional optional properties.
> +
> + clocks_node {
> + reg = <>;
> +
> + spll_node {
> + ...
> + };
> +
> + frcdiv_node {
> + ...
> + };
> +
> + sysclk_mux_node {
> + ...
> + };
> +
> + pbdiv_node {
> + ...
> + };
> +
> + refoclk_node {
> + ...
> + };
> + ...
> + };
> +
> +This binding uses the common clock binding[1].
> +
> +[1] Documentation/devicetree/bindings/clock/clock-bindings.txt
> +
> +Required properties:
> +- compatible : should be one of "microchip,pic32mzda-clk",
> + "microchip,pic32mzda-sosc", "microchip,pic32mzda-frcdivclk",
> + "microchip,pic32mzda-syspll", "microchip,pic32mzda-sysclk-v2",
> + "microchip,pic32mzda-pbclk", "microchip,pic32mzda-refoclk".
> +- reg : A Base address and length of the register set.
> +- interrupts : source of interrupt.
> +
> +Optional properties (for subnodes):
> +- #clock-cells: From common clock binding, should be 0.
> +- microchip,clock-indices: in multiplexer node clock sources always aren't linear
> + and contiguous. This property helps define clock-sources with respect to
> + the mux clock node.
> +- microchip,ignore-unused : ignore gate request even if the gated clock is unused.
> +- microchip,status-bit-mask: bitmask for status check. This will be used to confirm
> + particular operation by clock sub-node is completed. It is dependent sub-node.
> +- microchip,bit-mask: enable mask, similar to microchip,status-bit-mask.
> +- microchip,slew-step: enable frequency slewing(stepping) during rate change;
> + applicable only to sys-clock subnode.
> +
> +Example:
> +
> +/* PIC32 specific clks */
> +pic32_clktree {
> + #address-cells = <1>;
> + #size-cells = <1>;
> + reg = <0x1f801200 0x200>;
> + compatible = "microchip,pic32mzda-clk";
> + ranges = <0 0x1f801200 0x200>;
> +
> + /* secondary oscillator; external input on SOSCI pin */
> + SOSC:sosc_clk {

For the ones with reg property, do clock@0 instead of sosc_clk.

> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-sosc";
> + clock-frequency = <32768>;
> + reg = <0x000 0x10>, /* enable reg */
> + <0x1d0 0x10>; /* status reg */
> + microchip,bit-mask = <0x02>; /* enable mask */
> + microchip,status-bit-mask = <0x10>; /* status-mask*/
> + };
> +
> + FRCDIV:frcdiv_clk {
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-frcdivclk";
> + clocks = <&FRC>;
> + clock-output-names = "frcdiv_clk";
> + };
> +
> + /* System PLL clock */
> + SYSPLL:spll_clk {
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-syspll";
> + reg = <0x020 0x10>, /* SPLL register */
> + <0x1d0 0x10>; /* CLKSTAT register */
> + clocks = <&POSC>, <&FRC>;
> + clock-output-names = "sys_pll";
> + microchip,status-bit-mask = <0x80>; /* SPLLRDY */
> + };
> +
> + /* system clock; mux with postdiv & slew */
> + SYSCLK:sys_clk {
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-sysclk-v2";
> + reg = <0x1c0 0x04>; /* SLEWCON */
> + clocks = <&FRCDIV>, <&SYSPLL>, <&POSC>, <&SOSC>,
> + <&LPRC>, <&FRCDIV>;
> + microchip,clock-indices = <0>, <1>, <2>, <4>, <5>, <7>;
> + clock-output-names = "sys_clk";
> + };
> +
> + /* UPLL is integral part of USB PHY; UTMI clk for USBCORE */
> + UPLL:usb_phy_clk {
> + #clock-cells = <0>;
> + compatible = "fixed-clocks";
> + clock-frequency = <24000000>;
> + clock-output-names = "usbphy_clk";
> + };
> +
> + /* Peripheral bus1 clock */
> + PBCLK1:pb1_clk {
> + reg = <0x140 0x10>;
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-pbclk";
> + clocks = <&SYSCLK>;
> + clock-output-names = "pb1_clk";
> + /* used by system modules, not gateable */
> + microchip,ignore-unused;
> + };
> +
> + /* Peripheral bus2 clock */
> + PBCLK2:pb2_clk {
> + reg = <0x150 0x10>;
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-pbclk";
> + clocks = <&SYSCLK>;
> + clock-output-names = "pb2_clk";
> + /* avoid gating even if unused */
> + microchip,ignore-unused;
> + };
> +
> + /* Peripheral bus3 clock */
> + PBCLK3:pb3_clk {
> + reg = <0x160 0x10>;
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-pbclk";
> + clocks = <&SYSCLK>;
> + clock-output-names = "pb3_clk";
> + };
> +
> + /* Peripheral bus4 clock(I/O ports, GPIO) */
> + PBCLK4:pb4_clk {
> + reg = <0x170 0x10>;
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-pbclk";
> + clocks = <&SYSCLK>;
> + clock-output-names = "pb4_clk";
> + };
> +
> + /* Peripheral bus clock */
> + PBCLK5:pb5_clk {
> + reg = <0x180 0x10>;
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-pbclk";
> + clocks = <&SYSCLK>;
> + clock-output-names = "pb5_clk";
> + };
> +
> + /* Peripheral Bus6 clock; */
> + PBCLK6:pb6_clk {
> + reg = <0x190 0x10>;
> + compatible = "microchip,pic32mzda-pbclk";
> + clocks = <&SYSCLK>;
> + #clock-cells = <0>;
> + };
> +
> + /* Peripheral bus7 clock */
> + PBCLK7:pb7_clk {
> + reg = <0x1A0 0x10>;

lower case

> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-pbclk";
> + /* CPU is driven by this clock; so named */
> + clock-output-names = "cpu_clk";
> + clocks = <&SYSCLK>;
> + };
> +
> + /* Reference Oscillator clock for SPI/I2S */
> + REFCLKO1:refo1_clk {
> + reg = <0x080 0x20>;
> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-refoclk";
> + clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> + <&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> + microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> + <7>, <8>, <9>;
> + clock-output-names = "refo1_clk";
> + };
> +
> + /* Reference Oscillator clock for SQI */
> + REFCLKO2:refo2_clk {
> + reg = <0x0A0 0x20>;

lower case

> + #clock-cells = <0>;
> + compatible = "microchip,pic32mzda-refoclk";
> + clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> + <&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> + microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> + <7>, <8>, <9>;
> + clock-output-names = "refo2_clk";
> + };
> +
> + /* Reference Oscillator clock, ADC */
> + REFCLKO3:refo3_clk {
> + reg = <0x0C0 0x20>;

lower case

> + compatible = "microchip,pic32mzda-refoclk";
> + clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> + <&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> + microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> + <7>, <8>, <9>;
> + #clock-cells = <0>;
> + clock-output-names = "refo3_clk";
> + };
> +
> + /* Reference Oscillator clock */
> + REFCLKO4:refo4_clk {
> + reg = <0x0E0 0x20>;
> + compatible = "microchip,pic32mzda-refoclk";
> + clocks = <&SYSCLK>, <&PBCLK1>, <&POSC>, <&FRC>, <&LPRC>,
> + <&SOSC>, <&SYSPLL>, <&REFIx>, <&BFRC>;
> + microchip,clock-indices = <0>,<1>,<2>,<3>,<4>,<5>,<7>,
> + <8>,<9>;
> + #clock-cells = <0>;
> + clock-output-names = "refo4_clk";
> + };
> +
> + /* Reference Oscillator clock, LCD */
> + REFCLKO5:refo5_clk {
> + reg = <0x100 0x20>;
> + compatible = "microchip,pic32mzda-refoclk";
> + clocks = <&SYSCLK>,<&PBCLK1>,<&POSC>,<&FRC>,<&LPRC>,
> + <&SOSC>,<&SYSPLL>,<&REFIx>,<&BFRC>;
> + microchip,clock-indices = <0>, <1>, <2>, <3>, <4>, <5>,
> + <7>, <8>,<9>;
> + #clock-cells = <0>;
> + clock-output-names = "refo5_clk";
> + };
> +};
> +
> +The clock consumer should specify the desired clock by having the clocks in its
> +"clock" phandle cell. For example for UART:
> +
> +uart2: serial@<> {
> + compatible = "microchip,pic32mzda-uart";
> + reg = <>;
> + interrupts = <>;
> + clocks = <&PBCLK2>;
> +}
> --
> 1.7.9.5
>
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