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In the SD specification v7.10 the SD express card has been added. This new type of removable SD card, can be managed via a PCIe/NVMe based interface, while also allowing backwards compatibility towards the legacy SD interface. To keep the backwards compatibility, it's required to start the initialization through the legacy SD interface. If it turns out that the mmc host and the SD card, both supports the PCIe/NVMe interface, then a switch should be allowed. Therefore, let's introduce some basic support for this type of SD cards to the mmc core. The mmc host, should set MMC_CAP2_SD_EXP if it supports this interface and MMC_CAP2_SD_EXP_1_2V, if also 1.2V is supported, as to inform the core about it. To deal with the switch to the PCIe/NVMe interface, the mmc host is required to implement a new host ops, ->init_sd_express(). Based on the initial communication between the host and the card, host->ios.timing is set to either MMC_TIMING_SD_EXP or MMC_TIMING_SD_EXP_1_2V, depending on if 1.2V is supported or not. In this way, the mmc host can check these values in its ->init_sd_express() ops, to know how to proceed with the handover. Note that, to manage card insert/removal, the mmc core sticks with using the ->get_cd() callback, which means it's the host's responsibility to make sure it provides valid data, even if the card may be managed by PCIe/NVMe at the moment. As long as the card seems to be present, the mmc core keeps the card powered on. Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Christoph Hellwig <hch@lst.de> Cc: Rui Feng <rui_feng@realsil.com.cn> Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org> Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Link: https://lore.kernel.org/r/1603936636-3126-1-git-send-email-rui_feng@realsil.com.cn
29 lines
810 B
C
29 lines
810 B
C
/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* linux/drivers/mmc/core/sd_ops.h
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*
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* Copyright 2006-2007 Pierre Ossman
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*/
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#ifndef _MMC_SD_OPS_H
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#define _MMC_SD_OPS_H
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#include <linux/types.h>
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struct mmc_card;
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struct mmc_host;
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int mmc_app_set_bus_width(struct mmc_card *card, int width);
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int mmc_send_app_op_cond(struct mmc_host *host, u32 ocr, u32 *rocr);
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int mmc_send_if_cond(struct mmc_host *host, u32 ocr);
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int mmc_send_if_cond_pcie(struct mmc_host *host, u32 ocr);
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int mmc_send_relative_addr(struct mmc_host *host, unsigned int *rca);
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int mmc_app_send_scr(struct mmc_card *card);
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int mmc_sd_switch(struct mmc_card *card, int mode, int group,
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u8 value, u8 *resp);
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int mmc_app_sd_status(struct mmc_card *card, void *ssr);
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int mmc_app_cmd(struct mmc_host *host, struct mmc_card *card);
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#endif
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