mmc: tmio: add hook for custom busy_wait calculation

Newer SDHI variants can 'wait while busy' longer than the generic TMIO.
Provide a hook to get the maximum cycle count to wait for. If the hook
is not populated, fall back to a generic version which works well with
all older TMIO/SDHI variants.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Tested-by: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Link: https://lore.kernel.org/r/20201125213001.15003-3-wsa+renesas@sang-engineering.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

drivers/mmc/host/tmio_mmc.h

@@ -181,6 +181,7 @@ struct tmio_mmc_host {
 	void (*reset)(struct tmio_mmc_host *host);
 	bool (*check_retune)(struct tmio_mmc_host *host);
 	void (*fixup_request)(struct tmio_mmc_host *host, struct mmc_request *mrq);
+	unsigned int (*get_timeout_cycles)(struct tmio_mmc_host *host);
 
 	void (*prepare_hs400_tuning)(struct tmio_mmc_host *host);
 	void (*hs400_downgrade)(struct tmio_mmc_host *host);

drivers/mmc/host/tmio_mmc_core.c

@@ -887,16 +887,20 @@ static void tmio_mmc_set_bus_width(struct tmio_mmc_host *host,
 	sd_ctrl_write16(host, CTL_SD_MEM_CARD_OPT, reg);
 }
 
-static void tmio_mmc_max_busy_timeout(struct tmio_mmc_host *host)
+static unsigned int tmio_mmc_get_timeout_cycles(struct tmio_mmc_host *host)
 {
 	u16 val = sd_ctrl_read16(host, CTL_SD_MEM_CARD_OPT);
-	unsigned int clk_rate = host->mmc->actual_clock ?: host->mmc->f_max;
-	unsigned int cycles;
 
 	val = (val & CARD_OPT_TOP_MASK) >> CARD_OPT_TOP_SHIFT;
-	cycles = 1 << (13 + val);
+	return 1 << (13 + val);
+}
 
-	host->mmc->max_busy_timeout = cycles / (clk_rate / MSEC_PER_SEC);
+static void tmio_mmc_max_busy_timeout(struct tmio_mmc_host *host)
+{
+	unsigned int clk_rate = host->mmc->actual_clock ?: host->mmc->f_max;
+
+	host->mmc->max_busy_timeout = host->get_timeout_cycles(host) /
+				      (clk_rate / MSEC_PER_SEC);
 }
 
 /* Set MMC clock / power.
@@ -1116,6 +1120,9 @@ int tmio_mmc_host_probe(struct tmio_mmc_host *_host)
 	if (!(pdata->flags & TMIO_MMC_HAS_IDLE_WAIT))
 		_host->write16_hook = NULL;
 
+	if (pdata->flags & TMIO_MMC_USE_BUSY_TIMEOUT && !_host->get_timeout_cycles)
+		_host->get_timeout_cycles = tmio_mmc_get_timeout_cycles;
+
 	_host->set_pwr = pdata->set_pwr;
 
 	ret = tmio_mmc_init_ocr(_host);