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This converts the GPIO-based I2C-driver to using GPIO descriptors instead of the old global numberspace-based GPIO interface. We: - Convert the driver to unconditionally grab two GPIOs from the device by index 0 (SDA) and 1 (SCL) which will work fine with device tree and descriptor tables. The existing device trees will continue to work just like before, but without any roundtrip through the global numberspace. - Brutally convert all boardfiles still passing global GPIOs by registering descriptor tables associated with the devices instead so this driver does not need to keep supporting passing any GPIO numbers as platform data. There is no stepwise approach as elegant as this, I strongly prefer this big hammer over any antsteps for this conversion. This way the old GPIO numbers go away and NEVER COME BACK. Special conversion for the different boards utilizing I2C-GPIO: - EP93xx (arch/arm/mach-ep93xx): pretty straight forward as all boards were using the same two GPIO lines, just define these two in a lookup table for "i2c-gpio" and register these along with the device. None of them define any other platform data so just pass NULL as platform data. This platform selects GPIOLIB so all should be smooth. The pins appear on a gpiochip for bank "G" as pins 1 (SDA) and 0 (SCL). - IXP4 (arch/arm/mach-ixp4): descriptor tables have to be registered for each board separately. They all use "IXP4XX_GPIO_CHIP" so it is pretty straight forward. Most board define no other platform data than SCL/SDA so they can drop the #include of <linux/i2c-gpio.h> and assign NULL to platform data. The "goramo_mlr" (Goramo Multilink Router) board is a bit worrisome: it implements its own I2C bit-banging in the board file, and optionally registers an I2C serial port, but claims the same GPIO lines for itself in the board file. This is not going to work: there will be competition for the GPIO lines, so delete the optional extra I2C bus instead, no I2C devices are registered on it anyway, there are just hints that it may contain an EEPROM that may be accessed from userspace. This needs to be fixed up properly by the serial clock using I2C emulation so drop a note in the code. - KS8695 board acs5k (arch/arm/mach-ks8695/board-acs5.c) has some platform data in addition to the pins so it needs to be kept around sans GPIO lines. Its GPIO chip is named "KS8695" and the arch selects GPIOLIB. - PXA boards (arch/arm/mach-pxa/*) use some of the platform data so it needs to be preserved here. The viper board even registers two GPIO I2Cs. The gpiochip is named "gpio-pxa" and the arch selects GPIOLIB. - SA1100 Simpad (arch/arm/mach-sa1100/simpad.c) defines a GPIO I2C bus, and the arch selects GPIOLIB. - Blackfin boards (arch/blackfin/bf533 etc) for these I assume their I2C GPIOs refer to the local gpiochip defined in arch/blackfin/kernel/bfin_gpio.c names "BFIN-GPIO". The arch selects GPIOLIB. The boards get spiked with IF_ENABLED(I2C_GPIO) but that is a side effect of it being like that already (I would just have Kconfig select I2C_GPIO and get rid of them all.) I also delete any platform data set to 0 as it will get that value anyway from static declartions of platform data. - The MIPS selects GPIOLIB and the Alchemy machine is using two local GPIO chips, one of them has a GPIO I2C. We need to adjust the local offset from the global number space here. The ATH79 has a proper GPIO driver in drivers/gpio/gpio-ath79.c and AFAICT the chip is named "ath79-gpio" and the PB44 PCF857x expander spawns from this on GPIO 1 and 0. The latter board only use the platform data to specify pins so it can be cut altogether after this. - The MFD Silicon Motion SM501 is a special case. It dynamically spawns an I2C bus off the MFD using sm501_create_subdev(). We use an approach to dynamically create a machine descriptor table and attach this to the "SM501-LOW" or "SM501-HIGH" gpiochip. We use chip-local offsets to grab the right lines. We can get rid of two local static inline helpers as part of this refactoring. Cc: Steven Miao <realmz6@gmail.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Guenter Roeck <linux@roeck-us.net> Cc: Ville Syrjälä <ville.syrjala@linux.intel.com> Cc: Magnus Damm <magnus.damm@gmail.com> Cc: Ben Dooks <ben.dooks@codethink.co.uk> Cc: Heiko Schocher <hs@denx.de> Acked-by: Wu, Aaron <Aaron.Wu@analog.com> Acked-by: Olof Johansson <olof@lixom.net> Acked-by: Lee Jones <lee.jones@linaro.org> Acked-by: Ralf Baechle <ralf@linux-mips.org> Tested-by: Geert Uytterhoeven <geert+renesas@glider.be> Signed-off-by: Linus Walleij <linus.walleij@linaro.org> |
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Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.