[PATCH 1/2] mmc: dw_mmc: Handle late vmmc regulator with EPROBE_DEFER

Doug Anderson
2013-06-07T04:53:22Z

It is possible to specify a regulator that should be turned on when
dw_mmc is probed. This regulator is optional, though a warning will
be printed if it's missing. The fact that the regulator is optional
means that (at the moment) it's not possible to use a regulator that
probes _after_ dw_mmc.

Fix this limitation by adding the ability to make vmmc required. If a
vmmc-supply is specified in the device tree we'll assume that vmmc is
required.

Signed-off-by: Doug Anderson <dianders@chromium.org>
---
.../devicetree/bindings/mmc/synopsis-dw-mshc.txt | 3 +++
drivers/mmc/host/dw_mmc.c | 22 ++++++++++++++++++++--
include/linux/mmc/dw_mmc.h | 3 +++
3 files changed, 26 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt b/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
index 726fd21..b09d2d0 100644
--- a/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
+++ b/Documentation/devicetree/bindings/mmc/synopsis-dw-mshc.txt
@@ -55,6 +55,9 @@ Optional properties:

* broken-cd: as documented in mmc core bindings.

+* vmmc-supply: The phandle to the regulator to use for vmmc. If this is
+ specified we'll defer probe until we can find this regulator.
+
Aliases:

- All the MSHC controller nodes should be represented in the aliases node using
diff --git a/drivers/mmc/host/dw_mmc.c b/drivers/mmc/host/dw_mmc.c
index bc3a1bc..d3a0f8a 100644
--- a/drivers/mmc/host/dw_mmc.c
+++ b/drivers/mmc/host/dw_mmc.c
@@ -1987,8 +1987,17 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)

host->vmmc = devm_regulator_get(mmc_dev(mmc), "vmmc");
if (IS_ERR(host->vmmc)) {
- pr_info("%s: no vmmc regulator found\n", mmc_hostname(mmc));
+ ret = PTR_ERR(host->vmmc);
host->vmmc = NULL;
+
+ if (host->pdata->vmmc_required) {
+ if (ret != -EPROBE_DEFER)
+ pr_err("%s: vmmc required: %d\n",
+ mmc_hostname(mmc), ret);
+ goto err_setup_bus;
+ }
+ pr_info("%s: no vmmc regulator found %d\n", mmc_hostname(mmc),
+ ret);
} else {
ret = regulator_enable(host->vmmc);
if (ret) {
@@ -2026,7 +2035,7 @@ static int dw_mci_init_slot(struct dw_mci *host, unsigned int id)

err_setup_bus:
mmc_free_host(mmc);
- return -EINVAL;
+ return ret;
}

static void dw_mci_cleanup_slot(struct dw_mci_slot *slot, unsigned int id)
@@ -2162,6 +2171,13 @@ static struct dw_mci_board *dw_mci_parse_dt(struct dw_mci *host)
if (of_find_property(np, "enable-sdio-wakeup", NULL))
pdata->pm_caps |= MMC_PM_WAKE_SDIO_IRQ;

+ /*
+ * If vmmc is directly specified in the device tree then we'll assume
+ * it's required and honor EPROBE_DEFER so it can show up late.
+ */
+ if (of_find_property(np, "vmmc-supply", NULL))
+ pdata->vmmc_required = 1;
+
return pdata;
}

@@ -2352,6 +2368,8 @@ int dw_mci_probe(struct dw_mci *host)
/* We need at least one slot to succeed */
for (i = 0; i < host->num_slots; i++) {
ret = dw_mci_init_slot(host, i);
+ if (ret == -EPROBE_DEFER)
+ goto err_workqueue;
if (ret)
dev_dbg(host->dev, "slot %d init failed\n", i);
else
diff --git a/include/linux/mmc/dw_mmc.h b/include/linux/mmc/dw_mmc.h
index 198f0fa..e84d288 100644
--- a/include/linux/mmc/dw_mmc.h
+++ b/include/linux/mmc/dw_mmc.h
@@ -244,6 +244,9 @@ struct dw_mci_board {
/* delay in mS before detecting cards after interrupt */
u32 detect_delay_ms;

+ /* If true then we won't probe until vmmc is available */
+ bool vmmc_required;
+
int (*init)(u32 slot_id, irq_handler_t , void *);
int (*get_ro)(u32 slot_id);
int (*get_cd)(u32 slot_id);
--
1.8.3