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![Linus Walleij](/assets/img/avatar_default.png)
This converts the bit-banged GPIO SPI driver to looking up and using GPIO descriptors to get a handle on GPIO lines for SCK, MOSI, MISO and all CS lines. All existing board files are converted in one go to keep it all consistent. With these conversions I rarely find any interrim steps that makes any sense. Device tree probing and GPIO handling should work like before also after this patch. For board files, we stop using controller data to pass the GPIO line for chip select, instead we pass this as a GPIO descriptor lookup like everything else. In some s3c24xx machines the names of the SPI devices were set to "spi-gpio" rather than "spi_gpio" which can never have worked, I fixed it working (I guess) as part of this patch set. Sometimes I wonder how this code got upstream in the first place, it obviously is not tested. mach-s3c64xx/mach-smartq.c has the same problem and additionally defines the *same* GPIO line for MOSI and MISO which is not going to be accepted by gpiolib. As the lines were number 1,2,2 I assumed it was a typo and use lines 1,2,3. A comment gives awat that line 0 is chip select though no actual SPI device is provided for the LCD supposed to be on this bit-banged SPI bus. I left it intact instead of just deleting the bus though. Kill off board file code that try to initialize the SPI lines to the same values that they will later be set by the spi_gpio driver anyways. Given the huge number of weird things in these board files I do not think this code is very tested or put in with much afterthought anyways. In order to assert that we do not get performance regressions on this crucial bing-banged driver, a ran a script like this dumping the Ilitek ILI9322 regmap 10000 times (it has no caching obviously) on an otherwise idle system in two iterations before and after the patches: #!/bin/sh for run in `seq 10000` do cat /debug/regmap/spi0.0/registers > /dev/null done Before the patch: time test.sh real 3m 41.03s user 0m 29.41s sys 3m 7.22s time test.sh real 3m 44.24s user 0m 32.31s sys 3m 7.60s After the patch: time test.sh real 3m 41.32s user 0m 28.92s sys 3m 8.08s time test.sh real 3m 39.92s user 0m 30.20s sys 3m 5.56s So any performance differences seems to be in the error margin. Signed-off-by: Linus Walleij <linus.walleij@linaro.org> Acked-by: Olof Johansson <olof@lixom.net> Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com> Signed-off-by: Mark Brown <broonie@kernel.org>
25 lines
724 B
C
25 lines
724 B
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef __LINUX_SPI_GPIO_H
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#define __LINUX_SPI_GPIO_H
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/*
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* For each bitbanged SPI bus, set up a platform_device node with:
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* - name "spi_gpio"
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* - id the same as the SPI bus number it implements
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* - dev.platform data pointing to a struct spi_gpio_platform_data
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*
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* Use spi_board_info with these busses in the usual way.
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*
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* If the bitbanged bus is later switched to a "native" controller,
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* that platform_device and controller_data should be removed.
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*/
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/**
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* struct spi_gpio_platform_data - parameter for bitbanged SPI master
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* @num_chipselect: how many slaves to allow
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*/
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struct spi_gpio_platform_data {
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u16 num_chipselect;
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};
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#endif /* __LINUX_SPI_GPIO_H */
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