[PATCH V2 2/3] mmc: dw_mmc: Support voltage changes

Yuvaraj Kumar C D
2014-08-22T13:47:51Z

From: Doug Anderson <dianders@chromium.org>

For UHS cards we need the ability to switch voltages from 3.3V to
1.8V. Add support to the dw_mmc driver to handle this. Note that
dw_mmc needs a little bit of extra code since the interface needs a
special bit programmed to the CMD register while CMD11 is progressing.
This means adding a few extra states to the state machine to track.

Signed-off-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Yuvaraj Kumar C D <yuvaraj.cd@samsung.com>
---
changes since v1:
1. Added error message and return error in case of regulator_set_voltage() fail.
2. changed dw_mci_cmd_interrupt(host,pending | SDMMC_INT_CMD_DONE)
to dw_mci_cmd_interrupt(host,pending).
3. Removed unnecessary comments.

drivers/mmc/host/dw_mmc.c | 134 +++++++++++++++++++++++++++++++++++++++++---
drivers/mmc/host/dw_mmc.h | 5 +-
include/linux/mmc/dw_mmc.h | 2 +
3 files changed, 131 insertions(+), 10 deletions(-)

diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index aadb0d6..f20b4b8 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -29,6 +29,7 @@
#include <linux/irq.h>
#include <linux/mmc/host.h>
#include <linux/mmc/mmc.h>
+#include <linux/mmc/sd.h>
#include <linux/mmc/sdio.h>
#include <linux/mmc/dw_mmc.h>
#include <linux/bitops.h>
@@ -234,10 +235,13 @@ err:
}
#endif /* defined(CONFIG_DEBUG_FS) */

+static void mci_send_cmd(struct dw_mci_slot *slot, u32 cmd, u32 arg);
+
static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command *cmd)
{
struct mmc_data *data;
struct dw_mci_slot *slot = mmc_priv(mmc);
+ struct dw_mci *host = slot->host;
const struct dw_mci_drv_data *drv_data = slot->host->drv_data;
u32 cmdr;
cmd->error = -EINPROGRESS;
@@ -253,6 +257,31 @@ static u32 dw_mci_prepare_command(struct mmc_host *mmc, struct mmc_command *cmd)
else if (cmd->opcode != MMC_SEND_STATUS && cmd->data)
cmdr |= SDMMC_CMD_PRV_DAT_WAIT;

+ if (cmd->opcode == SD_SWITCH_VOLTAGE) {
+ u32 clk_en_a;
+
+ /* Special bit makes CMD11 not die */
+ cmdr |= SDMMC_CMD_VOLT_SWITCH;
+
+ /* Change state to continue to handle CMD11 weirdness */
+ WARN_ON(slot->host->state != STATE_SENDING_CMD);
+ slot->host->state = STATE_SENDING_CMD11;
+
+ /*
+ * We need to disable clock stop while doing voltage switch
+ * according to Voltage Switch Normal Scenario.
+ * It's assumed that by the next time the CLKENA is updated
+ * (when we set the clock next) that the voltage change will
+ * be over, so we don't bother setting any bits to synchronize
+ * with dw_mci_setup_bus().
+ */
+ clk_en_a = mci_readl(host, CLKENA);
+ clk_en_a &= ~(SDMMC_CLKEN_LOW_PWR << slot->id);
+ mci_writel(host, CLKENA, clk_en_a);
+ mci_send_cmd(slot, SDMMC_CMD_UPD_CLK |
+ SDMMC_CMD_PRV_DAT_WAIT, 0);
+ }
+
if (cmd->flags & MMC_RSP_PRESENT) {
/* We expect a response, so set this bit */
cmdr |= SDMMC_CMD_RESP_EXP;
@@ -775,11 +804,15 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
unsigned int clock = slot->clock;
u32 div;
u32 clk_en_a;
+ u32 sdmmc_cmd_bits = SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT;
+
+ /* We must continue to set bit 28 in CMD until the change is complete */
+ if (host->state == STATE_WAITING_CMD11_DONE)
+ sdmmc_cmd_bits |= SDMMC_CMD_VOLT_SWITCH;

if (!clock) {
mci_writel(host, CLKENA, 0);
- mci_send_cmd(slot,
- SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
+ mci_send_cmd(slot, sdmmc_cmd_bits, 0);
} else if (clock != host->current_speed || force_clkinit) {
div = host->bus_hz / clock;
if (host->bus_hz % clock && host->bus_hz > clock)
@@ -803,15 +836,13 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
mci_writel(host, CLKSRC, 0);

/* inform CIU */
- mci_send_cmd(slot,
- SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
+ mci_send_cmd(slot, sdmmc_cmd_bits, 0);

/* set clock to desired speed */
mci_writel(host, CLKDIV, div);

/* inform CIU */
- mci_send_cmd(slot,
- SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
+ mci_send_cmd(slot, sdmmc_cmd_bits, 0);

/* enable clock; only low power if no SDIO */
clk_en_a = SDMMC_CLKEN_ENABLE << slot->id;
@@ -820,8 +851,7 @@ static void dw_mci_setup_bus(struct dw_mci_slot *slot, bool force_clkinit)
mci_writel(host, CLKENA, clk_en_a);

/* inform CIU */
- mci_send_cmd(slot,
- SDMMC_CMD_UPD_CLK | SDMMC_CMD_PRV_DAT_WAIT, 0);
+ mci_send_cmd(slot, sdmmc_cmd_bits, 0);

/* keep the clock with reflecting clock dividor */
slot->__clk_old = clock << div;
@@ -897,6 +927,17 @@ static void dw_mci_queue_request(struct dw_mci *host, struct dw_mci_slot *slot,

slot->mrq = mrq;

+ if (host->state == STATE_WAITING_CMD11_DONE) {
+ dev_warn(&slot->mmc->class_dev,
+ "Voltage change didn't complete\n");
+ /*
+ * this case isn't expected to happen, so we can
+ * either crash here or just try to continue on
+ * in the closest possible state
+ */
+ host->state = STATE_IDLE;
+ }
+
if (host->state == STATE_IDLE) {
host->state = STATE_SENDING_CMD;
dw_mci_start_request(host, slot);
@@ -973,6 +1014,9 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
/* Slot specific timing and width adjustment */
dw_mci_setup_bus(slot, false);

+ if (slot->host->state == STATE_WAITING_CMD11_DONE && ios->clock != 0)
+ slot->host->state = STATE_IDLE;
+
switch (ios->power_mode) {
case MMC_POWER_UP:
if (!IS_ERR(mmc->supply.vmmc)) {
@@ -1016,6 +1060,59 @@ static void dw_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
}
}

+static int dw_mci_card_busy(struct mmc_host *mmc)
+{
+ struct dw_mci_slot *slot = mmc_priv(mmc);
+ u32 status;
+
+ /*
+ * Check the busy bit which is low when DAT[3:0]
+ * (the data lines) are 0000
+ */
+ status = mci_readl(slot->host, STATUS);
+
+ return !!(status & SDMMC_STATUS_BUSY);
+}
+
+static int dw_mci_switch_voltage(struct mmc_host *mmc, struct mmc_ios *ios)
+{
+ struct dw_mci_slot *slot = mmc_priv(mmc);
+ struct dw_mci *host = slot->host;
+ u32 uhs;
+ u32 v18 = SDMMC_UHS_18V << slot->id;
+ int min_uv, max_uv;
+ int ret;
+
+ /*
+ * Program the voltage. Note that some instances of dw_mmc may use
+ * the UHS_REG for this. For other instances (like exynos) the UHS_REG
+ * does no harm but you need to set the regulator directly. Try both.
+ */
+ uhs = mci_readl(host, UHS_REG);
+ if (ios->signal_voltage == MMC_SIGNAL_VOLTAGE_330) {
+ min_uv = 2700000;
+ max_uv = 3600000;
+ uhs &= ~v18;
+ } else {
+ min_uv = 1700000;
+ max_uv = 1950000;
+ uhs |= v18;
+ }
+ if (!IS_ERR(mmc->supply.vqmmc)) {
+ ret = regulator_set_voltage(mmc->supply.vqmmc, min_uv, max_uv);
+
+ if (ret) {
+ dev_err(&mmc->class_dev,
+ "Regulator set error %d: %d - %d\n",
+ ret, min_uv, max_uv);
+ return ret;
+ }
+ }
+ mci_writel(host, UHS_REG, uhs);
+
+ return 0;
+}
+
static int dw_mci_get_ro(struct mmc_host *mmc)
{
int read_only;
@@ -1158,6 +1255,9 @@ static const struct mmc_host_ops dw_mci_ops = {
.get_cd = dw_mci_get_cd,
.enable_sdio_irq = dw_mci_enable_sdio_irq,
.execute_tuning = dw_mci_execute_tuning,
+ .card_busy = dw_mci_card_busy,
+ .start_signal_voltage_switch = dw_mci_switch_voltage,
+
};

static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
@@ -1181,7 +1281,11 @@ static void dw_mci_request_end(struct dw_mci *host, struct mmc_request *mrq)
dw_mci_start_request(host, slot);
} else {
dev_vdbg(host->dev, "list empty\n");
- host->state = STATE_IDLE;
+
+ if (host->state == STATE_SENDING_CMD11)
+ host->state = STATE_WAITING_CMD11_DONE;
+ else
+ host->state = STATE_IDLE;
}

spin_unlock(&host->lock);
@@ -1292,8 +1396,10 @@ static void dw_mci_tasklet_func(unsigned long priv)

switch (state) {
case STATE_IDLE:
+ case STATE_WAITING_CMD11_DONE:
break;

+ case STATE_SENDING_CMD11:
case STATE_SENDING_CMD:
if (!test_and_clear_bit(EVENT_CMD_COMPLETE,
&host->pending_events))
@@ -1894,6 +2000,14 @@ static irqreturn_t dw_mci_interrupt(int irq, void *dev_id)
}

if (pending) {
+ /* Check volt switch first, since it can look like an error */
+ if ((host->state == STATE_SENDING_CMD11) &&
+ (pending & SDMMC_INT_VOLT_SWITCH)) {
+ mci_writel(host, RINTSTS, SDMMC_INT_VOLT_SWITCH);
+ pending &= ~SDMMC_INT_VOLT_SWITCH;
+ dw_mci_cmd_interrupt(host, pending);
+ }
+
if (pending & DW_MCI_CMD_ERROR_FLAGS) {
mci_writel(host, RINTSTS, DW_MCI_CMD_ERROR_FLAGS);
host->cmd_status = pending;
@@ -1999,7 +2113,9 @@ static void dw_mci_work_routine_card(struct work_struct *work)

switch (host->state) {
case STATE_IDLE:
+ case STATE_WAITING_CMD11_DONE:
break;
+ case STATE_SENDING_CMD11:
case STATE_SENDING_CMD:
mrq->cmd->error = -ENOMEDIUM;
if (!mrq->data)
diff --git a/drivers/mmc/host/dw_mmc.h b/drivers/mmc/host/dw_mmc.h
index 08fd956..01b99e8 100644
--- a/drivers/mmc/host/dw_mmc.h
+++ b/drivers/mmc/host/dw_mmc.h
@@ -99,6 +99,7 @@
#define SDMMC_INT_HLE BIT(12)
#define SDMMC_INT_FRUN BIT(11)
#define SDMMC_INT_HTO BIT(10)
+#define SDMMC_INT_VOLT_SWITCH BIT(10) /* overloads bit 10! */
#define SDMMC_INT_DRTO BIT(9)
#define SDMMC_INT_RTO BIT(8)
#define SDMMC_INT_DCRC BIT(7)
@@ -113,6 +114,7 @@
/* Command register defines */
#define SDMMC_CMD_START BIT(31)
#define SDMMC_CMD_USE_HOLD_REG BIT(29)
+#define SDMMC_CMD_VOLT_SWITCH BIT(28)
#define SDMMC_CMD_CCS_EXP BIT(23)
#define SDMMC_CMD_CEATA_RD BIT(22)
#define SDMMC_CMD_UPD_CLK BIT(21)
@@ -130,6 +132,7 @@
/* Status register defines */
#define SDMMC_GET_FCNT(x) (((x)>>17) & 0x1FFF)
#define SDMMC_STATUS_DMA_REQ BIT(31)
+#define SDMMC_STATUS_BUSY BIT(9)
/* FIFOTH register defines */
#define SDMMC_SET_FIFOTH(m, r, t) (((m) & 0x7) << 28 | \
((r) & 0xFFF) << 16 | \
@@ -150,7 +153,7 @@
#define SDMMC_GET_VERID(x) ((x) & 0xFFFF)
/* Card read threshold */
#define SDMMC_SET_RD_THLD(v, x) (((v) & 0x1FFF) << 16 | (x))
-
+#define SDMMC_UHS_18V BIT(0)
/* All ctrl reset bits */
#define SDMMC_CTRL_ALL_RESET_FLAGS \
(SDMMC_CTRL_RESET | SDMMC_CTRL_FIFO_RESET | SDMMC_CTRL_DMA_RESET)
diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
index 84e2827..0013669 100644
--- a/include/linux/mmc/dw_mmc.h
+++ b/include/linux/mmc/dw_mmc.h
@@ -26,6 +26,8 @@ enum dw_mci_state {
STATE_DATA_BUSY,
STATE_SENDING_STOP,
STATE_DATA_ERROR,
+ STATE_SENDING_CMD11,
+ STATE_WAITING_CMD11_DONE,
};

enum {
--
1.7.10.4