[RFC 4/7] mmc: tmio: Add UHS-I mode support

[Wolfram Sang <wsa@the-dreams.de>]

From: Ben Hutchings <ben.hutchings@codethink.co.uk>

Based on work by Shinobu Uehara and Ben Dooks.  This adds the voltage
switch operation needed for all UHS-I modes, but not the tuning needed
for SDR-104 which will come later.

The card_busy implementation is a bit of a guess, but works for me on
an R8A7790 chip.

Signed-off-by: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
---
 drivers/mmc/host/tmio_mmc.h     |  3 +++
 drivers/mmc/host/tmio_mmc_pio.c | 31 +++++++++++++++++++++++++++++++
 2 files changed, 34 insertions(+)

diff --git a/drivers/mmc/host/tmio_mmc.h b/drivers/mmc/host/tmio_mmc.h
index b44b5890290622..aabd36955e73fb 100644
--- a/drivers/mmc/host/tmio_mmc.h
+++ b/drivers/mmc/host/tmio_mmc.h
@@ -101,6 +101,9 @@ struct tmio_mmc_host {
 	void (*clk_disable)(struct tmio_mmc_host *host);
 	int (*multi_io_quirk)(struct mmc_card *card,
 			      unsigned int direction, int blk_size);
+
+	int (*start_signal_voltage_switch)(struct tmio_mmc_host *host,
+					   unsigned char signal_voltage);
 };
 
 struct tmio_mmc_host *tmio_mmc_host_alloc(struct platform_device *pdev);
diff --git a/drivers/mmc/host/tmio_mmc_pio.c b/drivers/mmc/host/tmio_mmc_pio.c
index ae81b34f17a5a5..081a3def9305c1 100644
--- a/drivers/mmc/host/tmio_mmc_pio.c
+++ b/drivers/mmc/host/tmio_mmc_pio.c
@@ -1012,12 +1012,43 @@ static int tmio_multi_io_quirk(struct mmc_card *card,
 	return blk_size;
 }
 
+static int tmio_mmc_start_signal_voltage_switch(struct mmc_host *mmc,
+	struct mmc_ios *ios)
+{
+	struct tmio_mmc_host *host = mmc_priv(mmc);
+
+	if (!host->start_signal_voltage_switch)
+		return 0;
+
+	return host->start_signal_voltage_switch(host, ios->signal_voltage);
+}
+
+static int tmio_mmc_card_busy(struct mmc_host *mmc)
+{
+	struct tmio_mmc_host *host = mmc_priv(mmc);
+	u32 status;
+
+	pm_runtime_get_sync(mmc_dev(mmc));
+	status = sd_ctrl_read32(host, CTL_STATUS);
+	pm_runtime_mark_last_busy(mmc_dev(mmc));
+	pm_runtime_put_autosuspend(mmc_dev(mmc));
+
+	/*
+	 * Card signals busy by pulling down all of DAT[3:0].  This status
+	 * flag appears to reflect DAT3.
+	 */
+	return !(status & TMIO_STAT_SIGSTATE_A);
+}
+
 static const struct mmc_host_ops tmio_mmc_ops = {
 	.request	= tmio_mmc_request,
 	.set_ios	= tmio_mmc_set_ios,
 	.get_ro         = tmio_mmc_get_ro,
 	.get_cd		= mmc_gpio_get_cd,
 	.enable_sdio_irq = tmio_mmc_enable_sdio_irq,
+	.start_signal_voltage_switch
+			= tmio_mmc_start_signal_voltage_switch,
+	.card_busy	= tmio_mmc_card_busy,
 	.multi_io_quirk	= tmio_multi_io_quirk,
 };
 
-- 
2.7.0