Adding bcm2835-sdhost driver, and an overlay to enable it
BCM2835 has two SD card interfaces. This driver uses the other one. bcm2835-sdhost: Error handling fix, and code clarification bcm2835-sdhost: Adding overclocking option Allow a different clock speed to be substitued for a requested 50MHz. This option is exposed using the "overclock_50" DT parameter. Note that the sdhost interface is restricted to integer divisions of core_freq, and the highest sensible option for a core_freq of 250MHz is 84 (250/3 = 83.3MHz), the next being 125 (250/2) which is much too high. Use at your own risk. bcm2835-sdhost: Round up the overclock, so 62 works for 62.5Mhz Also only warn once for each overclock setting. bcm2835-sdhost: Improve error handling and recovery 1) Expose the hw_reset method to the MMC framework, removing many internal calls by the driver. 2) Reduce overclock setting on error. 3) Increase timeout to cope with high capacity cards. 4) Add properties and parameters to control pio_limit and debug. 5) Reduce messages at probe time. bcm2835-sdhost: Further improve overclock back-off bcm2835-sdhost: Clear HBLC for PIO mode Also update pio_limit default in overlay README. bcm2835-sdhost: Add the ERASE capability See: https://github.com/raspberrypi/linux/issues/1076 bcm2835-sdhost: Ignore CRC7 for MMC CMD1 It seems that the sdhost interface returns CRC7 errors for CMD1, which is the MMC-specific SEND_OP_COND. Returning these errors to the MMC layer causes a downward spiral, but ignoring them seems to be harmless. bcm2835-mmc/sdhost: Remove ARCH_BCM2835 differences The bcm2835-mmc driver (and -sdhost driver that copied from it) contains code to handle SDIO interrupts in a threaded interrupt handler rather than waking the MMC framework thread. The change follows a patch from Russell King that adds the facility as the preferred way of working. However, the new code path is only present in ARCH_BCM2835 builds, which I have taken to be a way of testing the waters rather than making the change across the board; I can't see any technical reason why it wouldn't be enabled for MACH_BCM270X builds. So this patch standardises on the ARCH_BCM2835 code, removing the old code paths. bcm2835-sdhost: Don't log timeout errors unless debug=1 The MMC card-discovery process generates timeouts. This is expected behaviour, so reporting it to the user serves no purpose. Suppress the reporting of timeout errors unless the debug flag is on. bcm2835-sdhost: Add workaround for odd behaviour on some cards For reasons not understood, the sdhost driver fails when reading sectors very near the end of some SD cards. The problem could be related to the similar issue that reading the final sector of any card as part of a multiple read never completes, and the workaround is an extension of the mechanism introduced to solve that problem which ensures those sectors are always read singly. bcm2835-sdhost: Major revision This is a significant revision of the bcm2835-sdhost driver. It improves on the original in a number of ways: 1) Through the use of CMD23 for reads it appears to avoid problems reading some sectors on certain high speed cards. 2) Better atomicity to prevent crashes. 3) Higher performance. 4) Activity logging included, for easier diagnosis in the event of a problem. Signed-off-by:Phil Elwell <phil@raspberrypi.org> bcm2835-sdhost: Restore ATOMIC flag to PIO sg mapping Allocation problems have been seen in a wireless driver, and this is the only change which might have been responsible. SQUASH: bcm2835-sdhost: Only claim one DMA channel With both MMC controllers enabled there are few DMA channels left. The bcm2835-sdhost driver only uses DMA in one direction at a time, so it doesn't need to claim two channels. See: https://github.com/raspberrypi/linux/issues/1327 Signed-off-by:
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