mmc: sdhci: if MAX_CURRENT is 0, try getting current from regulator

The sd host controller spec indicates the the MAX_CURRENT value may
be returned as 0.  In this case other methods need to be used to
return the current.  If 0 is returned and there is a regulator,
ask the regulator for how much current is available.

Signed-off-by: Philip Rakity <prakity@marvell.com>
Signed-off-by: Mark F. Brown <mark.brown314@gmail.com>
Reviewed-by: Aaron Lu <aaron.lu@amd.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

2 files changed, 23 insertions, 6 deletions

diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index f4b8b4db3a9a..a0853d03b330 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -2837,6 +2837,13 @@ int sdhci_add_host(struct sdhci_host *host)
                              SDHCI_RETUNING_MODE_SHIFT;
 
         ocr_avail = 0;
+
+        host->vmmc = regulator_get(mmc_dev(mmc), "vmmc");
+        if (IS_ERR(host->vmmc)) {
+                pr_info("%s: no vmmc regulator found\n", mmc_hostname(mmc));
+                host->vmmc = NULL;
+        }
+
         /*
          * According to SD Host Controller spec v3.00, if the Host System
          * can afford more than 150mA, Host Driver should set XPC to 1. Also
@@ -2845,6 +2852,21 @@ int sdhci_add_host(struct sdhci_host *host)
          * value.
          */
         max_current_caps = sdhci_readl(host, SDHCI_MAX_CURRENT);
+        if (!max_current_caps && host->vmmc) {
+                u32 curr = regulator_get_current_limit(host->vmmc);
+                if (curr > 0) {
+
+                        /* convert to SDHCI_MAX_CURRENT format */
+                        curr = curr/1000;  /* convert to mA */
+                        curr = curr/SDHCI_MAX_CURRENT_MULTIPLIER;
+
+                        curr = min_t(u32, curr, SDHCI_MAX_CURRENT_LIMIT);
+                        max_current_caps =
+                                (curr << SDHCI_MAX_CURRENT_330_SHIFT) |
+                                (curr << SDHCI_MAX_CURRENT_300_SHIFT) |
+                                (curr << SDHCI_MAX_CURRENT_180_SHIFT);
+                }
+        }
 
         if (caps[0] & SDHCI_CAN_VDD_330) {
                 int max_current_330;
@@ -2995,12 +3017,6 @@ int sdhci_add_host(struct sdhci_host *host)
         if (ret)
                 goto untasklet;
 
-        host->vmmc = regulator_get(mmc_dev(mmc), "vmmc");
-        if (IS_ERR(host->vmmc)) {
-                pr_info("%s: no vmmc regulator found\n", mmc_hostname(mmc));
-                host->vmmc = NULL;
-        }
-
         sdhci_init(host, 0);
 
 #ifdef CONFIG_MMC_DEBUG
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index f761f23d2a28..97653ea8942b 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -205,6 +205,7 @@
 #define SDHCI_CAPABILITIES_1    0x44
 
 #define SDHCI_MAX_CURRENT               0x48
+#define  SDHCI_MAX_CURRENT_LIMIT        0xFF
 #define  SDHCI_MAX_CURRENT_330_MASK     0x0000FF
 #define  SDHCI_MAX_CURRENT_330_SHIFT    0
 #define  SDHCI_MAX_CURRENT_300_MASK     0x00FF00