This patch adds the power class selection feature available
for mmc versions 4.0 and above.
During the enumeration stage before switching to the lower
data bus, check if the power class is supported for the
current bus width. If the power class is available then
switch to the power class and use the higher data bus. If
power class is not supported then switch to the lower data
bus in a worst case.
Signed-off-by: Girish K S <girish.shivananjappa@xxxxxxxxxx>
---
v1:
This patch version modifies the power_class_select function prototype.
During device enumeration, when the host tries to read the extended
csd register after switching to higher bus width, the read fails at
higher bus width. So the power_class_select function is modified to
reuse the extended csd register values read with 1 bit bus width.
v2:
This patch version removes some checkpatch error
v3:
updated with review comments made by chris ball. patch generated
by rebasing to chris balls mmc-next branch.
drivers/mmc/core/mmc.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++
include/linux/mmc/mmc.h | 13 +++++++
2 files changed, 104 insertions(+), 0 deletions(-)
diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
index e3695a0..9dd6c82 100644
--- a/drivers/mmc/core/mmc.c
+++ b/drivers/mmc/core/mmc.c
@@ -536,6 +536,81 @@ static struct device_type mmc_type = {
};
/*
+ * Select the PowerClass for the current bus width
+ * If power class is defined for 4/8 bit bus in the
+ * extended CSD register, select it by executing the
+ * mmc_switch command.
+ */
+static int mmc_select_powerclass(struct mmc_card *card,
+ unsigned int bus_width, u8 *ext_csd)
+{
+ int err = 0;
+ unsigned int pwrclass_val;
+ unsigned int index = 0;
+ struct mmc_host *host = card->host;
+
+ BUG_ON(!card);
+ BUG_ON(!host);
+
+ if (ext_csd == NULL)
+ return 0;
+ /* Power class selection is supported for versions >= 4.0 */
+ if (card->csd.mmca_vsn < CSD_SPEC_VER_4)
+ return 0;
+ /* Power class values are defined only for 4/8 bit bus */
+ if (bus_width == EXT_CSD_BUS_WIDTH_1)
+ return 0;
+
+ switch (1 << host->ios.vdd) {
+ case MMC_VDD_165_195:
+ if (host->ios.clock <= 26000000)
+ index = EXT_CSD_PWR_CL_26_195;
+ else if (host->ios.clock <= 52000000)
+ index = (bus_width <= EXT_CSD_BUS_WIDTH_8) ?
+ EXT_CSD_PWR_CL_52_195 :
+ EXT_CSD_PWR_CL_DDR_52_195;
+ else if (host->ios.clock <= 200000000)
+ index = EXT_CSD_PWR_CL_200_195;
+ break;
+ case MMC_VDD_32_33:
+ case MMC_VDD_33_34:
+ case MMC_VDD_34_35:
+ case MMC_VDD_35_36:
+ if (host->ios.clock <= 26000000)
+ index = EXT_CSD_PWR_CL_26_360;
+ else if (host->ios.clock <= 52000000)
+ index = (bus_width <= EXT_CSD_BUS_WIDTH_8) ?
+ EXT_CSD_PWR_CL_52_360 :
+ EXT_CSD_PWR_CL_DDR_52_360;
+ else if (host->ios.clock <= 200000000)
+ index = EXT_CSD_PWR_CL_200_360;
+ break;
+ default:
+ printk(KERN_ERR "votage range not supported\n");
+ break;
+ }
+
+ pwrclass_val = ext_csd[index];
+
+ if (bus_width & (EXT_CSD_BUS_WIDTH_8 | EXT_CSD_DDR_BUS_WIDTH_8))
+ pwrclass_val = (pwrclass_val & EXT_CSD_PWR_CL_8BIT_MASK) >>
+ EXT_CSD_PWR_CL_8BIT_SHIFT;
+ else
+ pwrclass_val = (pwrclass_val & EXT_CSD_PWR_CL_4BIT_MASK) >>
+ EXT_CSD_PWR_CL_4BIT_SHIFT;
+
+ /*If the power class is different from the default value*/
+ if (pwrclass_val > 0) {
+ err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
+ EXT_CSD_POWER_CLASS,
+ pwrclass_val,
+ 0);
+ }
+
+ return err;
+}
+
+/*
* Handle the detection and initialisation of a card.
*
* In the case of a resume, "oldcard" will contain the card
@@ -807,6 +882,14 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
bus_width = bus_widths[idx];
if (bus_width == MMC_BUS_WIDTH_1)
ddr = 0; /* no DDR for 1-bit width */
+ err = mmc_select_powerclass(card, ext_csd_bits[idx][0],
+ ext_csd);
+ if (err)
+ printk(KERN_ERR "%s: power class selection to "
+ "bus width %d failed\n",
+ mmc_hostname(card->host),
+ 1 << bus_width);
+
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
EXT_CSD_BUS_WIDTH,
ext_csd_bits[idx][0],
@@ -830,6 +913,14 @@ static int mmc_init_card(struct mmc_host *host, u32 ocr,
}
if (!err && ddr) {
+ err = mmc_select_powerclass(card, ext_csd_bits[idx][1],
+ ext_csd);
+ if (err)
+ printk(KERN_ERR "%s: power class selection to "
+ "bus width %d ddr %d failed\n",
+ mmc_hostname(card->host),
+ 1 << bus_width, ddr);
+
err = mmc_switch(card, EXT_CSD_CMD_SET_NORMAL,
EXT_CSD_BUS_WIDTH,
ext_csd_bits[idx][1],
diff --git a/include/linux/mmc/mmc.h b/include/linux/mmc/mmc.h
index 95912da..d72d550 100644
--- a/include/linux/mmc/mmc.h
+++ b/include/linux/mmc/mmc.h
@@ -280,10 +280,15 @@ struct _mmc_csd {
#define EXT_CSD_ERASED_MEM_CONT 181 /* RO */
#define EXT_CSD_BUS_WIDTH 183 /* R/W */
#define EXT_CSD_HS_TIMING 185 /* R/W */
+#define EXT_CSD_POWER_CLASS 187
#define EXT_CSD_REV 192 /* RO */
#define EXT_CSD_STRUCTURE 194 /* RO */
#define EXT_CSD_CARD_TYPE 196 /* RO */
#define EXT_CSD_PART_SWITCH_TIME 199 /* RO */
+#define EXT_CSD_PWR_CL_52_195 200 /*RO*/
+#define EXT_CSD_PWR_CL_26_195 201 /*RO*/
+#define EXT_CSD_PWR_CL_52_360 202 /*RO*/
+#define EXT_CSD_PWR_CL_26_360 203 /*RO*/
#define EXT_CSD_SEC_CNT 212 /* RO, 4 bytes */
#define EXT_CSD_S_A_TIMEOUT 217 /* RO */
#define EXT_CSD_REL_WR_SEC_C 222 /* RO */
@@ -295,6 +300,10 @@ struct _mmc_csd {
#define EXT_CSD_SEC_ERASE_MULT 230 /* RO */
#define EXT_CSD_SEC_FEATURE_SUPPORT 231 /* RO */
#define EXT_CSD_TRIM_MULT 232 /* RO */
+#define EXT_CSD_PWR_CL_200_195 236 /*RO*/
+#define EXT_CSD_PWR_CL_200_360 237 /*RO*/
+#define EXT_CSD_PWR_CL_DDR_52_195 238 /*RO*/
+#define EXT_CSD_PWR_CL_DDR_52_360 239 /*RO*/
#define EXT_CSD_POWER_OFF_LONG_TIME 247 /*RO*/
/*
@@ -338,6 +347,10 @@ struct _mmc_csd {
#define EXT_CSD_POWER_OFF_SHORT 2
#define EXT_CSD_POWER_OFF_LONG 3
+#define EXT_CSD_PWR_CL_8BIT_MASK 0xF0/* 8 bit PWR CLS */
+#define EXT_CSD_PWR_CL_4BIT_MASK 0x0F/* 8 bit PWR CLS */
+#define EXT_CSD_PWR_CL_8BIT_SHIFT 4
+#define EXT_CSD_PWR_CL_4BIT_SHIFT 0
/*
* MMC_SWITCH access modes
*/
--
1.7.1
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