mmc: sd: set current limit for uhs cards

We decide on the current limit to be set for the card based on the
Capability of Host Controller to provide current at 1.8V signalling,
and the maximum current limit of the card as indicated by CMD6
mode 0. We then set the current limit for the card using CMD6 mode 1.
As per the Physical Layer Spec v3.01, the current limit switch is
only applicable for SDR50, SDR104, and DDR50 bus speed modes. For
other UHS-I modes, we set the default current limit of 200mA.

Tested by Zhangfei Gao with a Toshiba uhs card and general hs card,
on mmp2 in SDMA mode.

Signed-off-by: Arindam Nath <arindam.nath@amd.com>
Reviewed-by: Philip Rakity <prakity@marvell.com>
Tested-by: Philip Rakity <prakity@marvell.com>
Acked-by: Zhangfei Gao <zhangfei.gao@marvell.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 13 insertions, 0 deletions

diff --git a/include/linux/mmc/card.h b/include/linux/mmc/card.h
index 4ef6ded6347d..47b5ad3960b7 100644
--- a/include/linux/mmc/card.h
+++ b/include/linux/mmc/card.h
@@ -105,6 +105,15 @@ struct sd_switch_caps {
 #define SD_DRIVER_TYPE_C        0x04
 #define SD_DRIVER_TYPE_D        0x08
         unsigned int            sd3_curr_limit;
+#define SD_SET_CURRENT_LIMIT_200        0
+#define SD_SET_CURRENT_LIMIT_400        1
+#define SD_SET_CURRENT_LIMIT_600        2
+#define SD_SET_CURRENT_LIMIT_800        3
+
+#define SD_MAX_CURRENT_200      (1 << SD_SET_CURRENT_LIMIT_200)
+#define SD_MAX_CURRENT_400      (1 << SD_SET_CURRENT_LIMIT_400)
+#define SD_MAX_CURRENT_600      (1 << SD_SET_CURRENT_LIMIT_600)
+#define SD_MAX_CURRENT_800      (1 << SD_SET_CURRENT_LIMIT_800)
 };
 
 struct sdio_cccr {
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index 62375992bdd6..52b5dc914a8c 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -203,6 +203,10 @@ struct mmc_host {
 #define MMC_CAP_DRIVER_TYPE_A   (1 << 23)       /* Host supports Driver Type A */
 #define MMC_CAP_DRIVER_TYPE_C   (1 << 24)       /* Host supports Driver Type C */
 #define MMC_CAP_DRIVER_TYPE_D   (1 << 25)       /* Host supports Driver Type D */
+#define MMC_CAP_MAX_CURRENT_200 (1 << 26)       /* Host max current limit is 200mA */
+#define MMC_CAP_MAX_CURRENT_400 (1 << 27)       /* Host max current limit is 400mA */
+#define MMC_CAP_MAX_CURRENT_600 (1 << 28)       /* Host max current limit is 600mA */
+#define MMC_CAP_MAX_CURRENT_800 (1 << 29)       /* Host max current limit is 800mA */
 
         mmc_pm_flag_t           pm_caps;        /* supported pm features */