mmc: core: Export a function mmc_sw_reset() to allow soft reset of cards (1433269c) · Commits · 戴 / test

It's rather common that a firmware is loaded into an SDIO func device memory, by the corresponding SDIO func driver during ->probe() time. However, to actually start running the new firmware, sometimes a soft reset (no power cycle) and a re-initialization of the card is needed. This is for example the case with the Espressif ESP8089 WiFi chips, when connected to an SDIO interface. To cope with this scenario, let's add a new exported function, mmc_sw_reset(), which may be called when a soft reset and re-initialization of the card are needed. The mmc_sw_reset() is implemented on top of a new bus ops callback, similar to how the mmc_hw_reset() has been implemented. Signed-off-by:

Ulf Hansson <ulf.hansson@linaro.org> Tested-by:

Quentin Schulz <quentin.schulz@bootlin.com> Reviewed-by:

Shawn Lin <shawn.lin@rock-chips.com>

drivers/mmc/core/core.c

+24 −0

Original line number	Diff line number	Diff line
		@@ -2451,6 +2451,30 @@ int mmc_hw_reset(struct mmc_host *host)
		}
		EXPORT_SYMBOL(mmc_hw_reset);

		int mmc_sw_reset(struct mmc_host *host)
		{
		int ret;

		if (!host->card)
		return -EINVAL;

		mmc_bus_get(host);
		if (!host->bus_ops \|\| host->bus_dead \|\| !host->bus_ops->sw_reset) {
		mmc_bus_put(host);
		return -EOPNOTSUPP;
		}

		ret = host->bus_ops->sw_reset(host);
		mmc_bus_put(host);

		if (ret)
		pr_warn("%s: tried to SW reset card, got error %d\n",
		mmc_hostname(host), ret);

		return ret;
		}
		EXPORT_SYMBOL(mmc_sw_reset);

		static int mmc_rescan_try_freq(struct mmc_host *host, unsigned freq)
		{
		host->f_init = freq;

drivers/mmc/core/core.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -33,6 +33,7 @@ struct mmc_bus_ops {
		int (alive)(struct mmc_host );
		int (shutdown)(struct mmc_host );
		int (hw_reset)(struct mmc_host );
		int (sw_reset)(struct mmc_host );
		};

		void mmc_attach_bus(struct mmc_host host, const struct mmc_bus_ops ops);

include/linux/mmc/core.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -177,6 +177,7 @@ int mmc_wait_for_cmd(struct mmc_host host, struct mmc_command cmd,
		int retries);

		int mmc_hw_reset(struct mmc_host *host);
		int mmc_sw_reset(struct mmc_host *host);
		void mmc_set_data_timeout(struct mmc_data data, const struct mmc_card card);

		#endif /* LINUX_MMC_CORE_H */

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