diff options
author | Bin Meng <bmeng.cn@gmail.com> | 2019-07-18 10:33:55 +0300 |
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committer | Tom Rini <trini@konsulko.com> | 2019-07-24 17:07:24 +0300 |
commit | 45dbb4dd23a0bcbeee66540e5baa85d549ac95fb (patch) | |
tree | 0eb0b5eae04cc02f8cda84a30d2a9d956c93c02d /doc | |
parent | 6c49c22846807375caf434b08f8f2b9d48cf5513 (diff) | |
download | u-boot-45dbb4dd23a0bcbeee66540e5baa85d549ac95fb.tar.xz |
doc: driver-model: Convert of-plat.txt to reST
Convert plain text documentation to reStructuredText format and add
it to Sphinx TOC tree. No essential content change.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Diffstat (limited to 'doc')
-rw-r--r-- | doc/driver-model/index.rst | 1 | ||||
-rw-r--r-- | doc/driver-model/of-plat.rst (renamed from doc/driver-model/of-plat.txt) | 193 |
2 files changed, 106 insertions, 88 deletions
diff --git a/doc/driver-model/index.rst b/doc/driver-model/index.rst index ff9b18350c..d1c19a4103 100644 --- a/doc/driver-model/index.rst +++ b/doc/driver-model/index.rst @@ -12,3 +12,4 @@ Driver Model i2c-howto livetree migration + of-plat diff --git a/doc/driver-model/of-plat.txt b/doc/driver-model/of-plat.rst index 0109ec56c3..0d3cd8c01e 100644 --- a/doc/driver-model/of-plat.txt +++ b/doc/driver-model/of-plat.rst @@ -1,5 +1,7 @@ -Driver Model Compiled-in Device Tree / Platform Data -==================================================== +.. SPDX-License-Identifier: GPL-2.0+ + +Compiled-in Device Tree / Platform Data +======================================= Introduction @@ -40,36 +42,36 @@ There are many problems with this features. It should only be used when strictly necessary. Notable problems include: - Device tree does not describe data types. But the C code must define a - type for each property. These are guessed using heuristics which - are wrong in several fairly common cases. For example an 8-byte value - is considered to be a 2-item integer array, and is byte-swapped. A - boolean value that is not present means 'false', but cannot be - included in the structures since there is generally no mention of it - in the device tree file. + type for each property. These are guessed using heuristics which + are wrong in several fairly common cases. For example an 8-byte value + is considered to be a 2-item integer array, and is byte-swapped. A + boolean value that is not present means 'false', but cannot be + included in the structures since there is generally no mention of it + in the device tree file. - Naming of nodes and properties is automatic. This means that they follow - the naming in the device tree, which may result in C identifiers that - look a bit strange. + the naming in the device tree, which may result in C identifiers that + look a bit strange. - It is not possible to find a value given a property name. Code must use - the associated C member variable directly in the code. This makes - the code less robust in the face of device-tree changes. It also - makes it very unlikely that your driver code will be useful for more - than one SoC. Even if the code is common, each SoC will end up with - a different C struct name, and a likely a different format for the - platform data. + the associated C member variable directly in the code. This makes + the code less robust in the face of device-tree changes. It also + makes it very unlikely that your driver code will be useful for more + than one SoC. Even if the code is common, each SoC will end up with + a different C struct name, and a likely a different format for the + platform data. - The platform data is provided to drivers as a C structure. The driver - must use the same structure to access the data. Since a driver - normally also supports device tree it must use #ifdef to separate - out this code, since the structures are only available in SPL. + must use the same structure to access the data. Since a driver + normally also supports device tree it must use #ifdef to separate + out this code, since the structures are only available in SPL. - Correct relations between nodes are not implemented. This means that - parent/child relations (like bus device iteration) do not work yet. - Some phandles (those that are recognised as such) are converted into - a pointer to platform data. This pointer can potentially be used to - access the referenced device (by searching for the pointer value). - This feature is not yet implemented, however. + parent/child relations (like bus device iteration) do not work yet. + Some phandles (those that are recognised as such) are converted into + a pointer to platform data. This pointer can potentially be used to + access the referenced device (by searching for the pointer value). + This feature is not yet implemented, however. How it works @@ -78,30 +80,34 @@ How it works The feature is enabled by CONFIG OF_PLATDATA. This is only available in SPL/TPL and should be tested with: - #if CONFIG_IS_ENABLED(OF_PLATDATA) +.. code-block:: c + + #if CONFIG_IS_ENABLED(OF_PLATDATA) A new tool called 'dtoc' converts a device tree file either into a set of struct declarations, one for each compatible node, and a set of U_BOOT_DEVICE() declarations along with the actual platform data for each device. As an example, consider this MMC node: - sdmmc: dwmmc@ff0c0000 { - compatible = "rockchip,rk3288-dw-mshc"; - clock-freq-min-max = <400000 150000000>; - clocks = <&cru HCLK_SDMMC>, <&cru SCLK_SDMMC>, - <&cru SCLK_SDMMC_DRV>, <&cru SCLK_SDMMC_SAMPLE>; - clock-names = "biu", "ciu", "ciu_drv", "ciu_sample"; - fifo-depth = <0x100>; - interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>; - reg = <0xff0c0000 0x4000>; - bus-width = <4>; - cap-mmc-highspeed; - cap-sd-highspeed; - card-detect-delay = <200>; - disable-wp; - num-slots = <1>; - pinctrl-names = "default"; - pinctrl-0 = <&sdmmc_clk>, <&sdmmc_cmd>, <&sdmmc_cd>, <&sdmmc_bus4>; +.. code-block:: none + + sdmmc: dwmmc@ff0c0000 { + compatible = "rockchip,rk3288-dw-mshc"; + clock-freq-min-max = <400000 150000000>; + clocks = <&cru HCLK_SDMMC>, <&cru SCLK_SDMMC>, + <&cru SCLK_SDMMC_DRV>, <&cru SCLK_SDMMC_SAMPLE>; + clock-names = "biu", "ciu", "ciu_drv", "ciu_sample"; + fifo-depth = <0x100>; + interrupts = <GIC_SPI 32 IRQ_TYPE_LEVEL_HIGH>; + reg = <0xff0c0000 0x4000>; + bus-width = <4>; + cap-mmc-highspeed; + cap-sd-highspeed; + card-detect-delay = <200>; + disable-wp; + num-slots = <1>; + pinctrl-names = "default"; + pinctrl-0 = <&sdmmc_clk>, <&sdmmc_cmd>, <&sdmmc_cd>, <&sdmmc_bus4>; vmmc-supply = <&vcc_sd>; status = "okay"; u-boot,dm-pre-reloc; @@ -112,52 +118,59 @@ Some of these properties are dropped by U-Boot under control of the CONFIG_OF_SPL_REMOVE_PROPS option. The rest are processed. This will produce the following C struct declaration: -struct dtd_rockchip_rk3288_dw_mshc { - fdt32_t bus_width; - bool cap_mmc_highspeed; - bool cap_sd_highspeed; - fdt32_t card_detect_delay; - fdt32_t clock_freq_min_max[2]; - struct phandle_1_arg clocks[4]; - bool disable_wp; - fdt32_t fifo_depth; - fdt32_t interrupts[3]; - fdt32_t num_slots; - fdt32_t reg[2]; - fdt32_t vmmc_supply; -}; +.. code-block:: c + + struct dtd_rockchip_rk3288_dw_mshc { + fdt32_t bus_width; + bool cap_mmc_highspeed; + bool cap_sd_highspeed; + fdt32_t card_detect_delay; + fdt32_t clock_freq_min_max[2]; + struct phandle_1_arg clocks[4]; + bool disable_wp; + fdt32_t fifo_depth; + fdt32_t interrupts[3]; + fdt32_t num_slots; + fdt32_t reg[2]; + fdt32_t vmmc_supply; + }; and the following device declaration: -static struct dtd_rockchip_rk3288_dw_mshc dtv_dwmmc_at_ff0c0000 = { - .fifo_depth = 0x100, - .cap_sd_highspeed = true, - .interrupts = {0x0, 0x20, 0x4}, - .clock_freq_min_max = {0x61a80, 0x8f0d180}, - .vmmc_supply = 0xb, - .num_slots = 0x1, - .clocks = {{&dtv_clock_controller_at_ff760000, 456}, - {&dtv_clock_controller_at_ff760000, 68}, - {&dtv_clock_controller_at_ff760000, 114}, - {&dtv_clock_controller_at_ff760000, 118}}, - .cap_mmc_highspeed = true, - .disable_wp = true, - .bus_width = 0x4, - .u_boot_dm_pre_reloc = true, - .reg = {0xff0c0000, 0x4000}, - .card_detect_delay = 0xc8, -}; -U_BOOT_DEVICE(dwmmc_at_ff0c0000) = { - .name = "rockchip_rk3288_dw_mshc", - .platdata = &dtv_dwmmc_at_ff0c0000, - .platdata_size = sizeof(dtv_dwmmc_at_ff0c0000), -}; +.. code-block:: c + + static struct dtd_rockchip_rk3288_dw_mshc dtv_dwmmc_at_ff0c0000 = { + .fifo_depth = 0x100, + .cap_sd_highspeed = true, + .interrupts = {0x0, 0x20, 0x4}, + .clock_freq_min_max = {0x61a80, 0x8f0d180}, + .vmmc_supply = 0xb, + .num_slots = 0x1, + .clocks = {{&dtv_clock_controller_at_ff760000, 456}, + {&dtv_clock_controller_at_ff760000, 68}, + {&dtv_clock_controller_at_ff760000, 114}, + {&dtv_clock_controller_at_ff760000, 118}}, + .cap_mmc_highspeed = true, + .disable_wp = true, + .bus_width = 0x4, + .u_boot_dm_pre_reloc = true, + .reg = {0xff0c0000, 0x4000}, + .card_detect_delay = 0xc8, + }; + + U_BOOT_DEVICE(dwmmc_at_ff0c0000) = { + .name = "rockchip_rk3288_dw_mshc", + .platdata = &dtv_dwmmc_at_ff0c0000, + .platdata_size = sizeof(dtv_dwmmc_at_ff0c0000), + }; The device is then instantiated at run-time and the platform data can be accessed using: - struct udevice *dev; - struct dtd_rockchip_rk3288_dw_mshc *plat = dev_get_platdata(dev); +.. code-block:: c + + struct udevice *dev; + struct dtd_rockchip_rk3288_dw_mshc *plat = dev_get_platdata(dev); This avoids the code overhead of converting the device tree data to platform data in the driver. The ofdata_to_platdata() method should @@ -173,7 +186,9 @@ each 'compatible' string. Where a node has multiple compatible strings, a #define is used to make them equivalent, e.g.: -#define dtd_rockchip_rk3299_dw_mshc dtd_rockchip_rk3288_dw_mshc +.. code-block:: c + + #define dtd_rockchip_rk3299_dw_mshc dtd_rockchip_rk3288_dw_mshc Converting of-platdata to a useful form @@ -204,6 +219,8 @@ ofdata_to_platdata() method and wrapped with #if. For example: +.. code-block:: c + #include <dt-structs.h> struct mmc_platdata { @@ -313,12 +330,12 @@ This is an implementation of an idea by Tom Rini <trini@konsulko.com>. Future work ----------- - Consider programmatically reading binding files instead of device tree - contents + contents - Complete the phandle feature - Move to using a full Python libfdt module --- -Simon Glass <sjg@chromium.org> -Google, Inc -6/6/16 -Updated Independence Day 2016 + +.. Simon Glass <sjg@chromium.org> +.. Google, Inc +.. 6/6/16 +.. Updated Independence Day 2016 |