Re: [PATCH v7 05/15] dt-bindings: Document the STM32 reset bindings

[Daniel Thompson <daniel.thompson@linaro.org>]

On 30/04/15 17:20, Maxime Coquelin wrote:
> This adds documentation of device tree bindings for the
> STM32 reset controller.
>
> Tested-by: Chanwoo Choi <cw00.choi@samsung.com>
> Acked-by: Philipp Zabel <p.zabel@pengutronix.de>
> Acked-by: Rob Herring <robh@kernel.org>
> Signed-off-by: Maxime Coquelin <mcoquelin.stm32@gmail.com>
> ---
>   .../devicetree/bindings/reset/st,stm32-rcc.txt     | 107 +++++++++++++++++++++
>   1 file changed, 107 insertions(+)
>   create mode 100644 Documentation/devicetree/bindings/reset/st,stm32-rcc.txt
>
> diff --git a/Documentation/devicetree/bindings/reset/st,stm32-rcc.txt b/Documentation/devicetree/bindings/reset/st,stm32-rcc.txt
> new file mode 100644
> index 0000000..c1b0f8d
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/reset/st,stm32-rcc.txt
> @@ -0,0 +1,107 @@
> +STMicroelectronics STM32 Peripheral Reset Controller
> +====================================================
> +
> +The RCC IP is both a reset and a clock controller. This documentation only
> +documents the reset part.
> +
> +Please also refer to reset.txt in this directory for common reset
> +controller binding usage.
> +
> +Required properties:
> +- compatible: Should be "st,stm32-rcc"
> +- reg: should be register base and length as documented in the
> +  datasheet
> +- #reset-cells: 1, see below
> +
> +example:
> +
> +rcc: reset@40023800 {
> +	#reset-cells = <1>;
> +	compatible = "st,stm32-rcc";

Do you intend the clock driver to use the same compatible string (given 
it is the same bit of hardware).

If so, is it better to use st,stm32f4-rcc here? It seems unlikey to me 
that the register layout of the PLLs and dividers can be the same on the 
f7 parts (and later).

> +	reg = <0x40023800 0x400>;
> +};
> +
> +Specifying softreset control of devices
> +=======================================
> +
> +Device nodes should specify the reset channel required in their "resets"
> +property, containing a phandle to the reset device node and an index specifying
> +which channel to use.
> +The index is the bit number within the RCC registers bank, starting from RCC
> +base address.
> +It is calculated as: index = register_offset / 4 * 32 + bit_offset.
> +Where bit_offset is the bit offset within the register.
> +For example, for CRC reset:
> +  crc = AHB1RSTR_offset / 4 * 32 + CRCRST_bit_offset = 0x10 / 4 * 32 + 12 = 140
> +
> +example:
> +
> +	timer2 {
> +		resets			= <&rcc 256>;
> +	};
> +
> +List of valid indices for STM32F429:
> + - gpioa: 128
> + - gpiob: 129
> + - gpioc: 130
> + - gpiod: 131
> + - gpioe: 132
> + - gpiof: 133
> + - gpiog: 134
> + - gpioh: 135
> + - gpioi: 136
> + - gpioj: 137
> + - gpiok: 138
> + - crc: 140
> + - dma1: 149
> + - dma2: 150
> + - dma2d: 151
> + - ethmac: 153
> + - otghs: 157
> + - dcmi: 160
> + - cryp: 164
> + - hash: 165
> + - rng: 166
> + - otgfs: 167
> + - fmc: 192
> + - tim2: 256
> + - tim3: 257
> + - tim4: 258
> + - tim5: 259
> + - tim6: 260
> + - tim7: 261
> + - tim12: 262
> + - tim13: 263
> + - tim14: 264
> + - wwdg: 267
> + - spi2: 270
> + - spi3: 271
> + - uart2: 273
> + - uart3: 274
> + - uart4: 275
> + - uart5: 276
> + - i2c1: 277
> + - i2c2: 278
> + - i2c3: 279
> + - can1: 281
> + - can2: 282
> + - pwr: 284
> + - dac: 285
> + - uart7: 286
> + - uart8: 287
> + - tim1: 288
> + - tim8: 289
> + - usart1: 292
> + - usart6: 293
> + - adc: 296
> + - sdio: 299
> + - spi1: 300
> + - spi4: 301
> + - syscfg: 302
> + - tim9: 304
> + - tim10: 305
> + - tim11: 306
> + - spi5: 308
> + - spi6: 309
> + - sai1: 310
> + - ltdc: 314

These numbers are stable for all STM32F4 family parts. Should this table 
go into a dt-bindings header file?