mmc: debugfs: expose the SDCLK frq in sys ios

This patch is to expose the actual SDCLK frequency in
/sys/kernel/debug/mmcX/ios entry.

For example, if the max clk for a normal speed card is 20MHz this
is reported in /sys/kernel/debug/mmcX/ios.  Unfortunately the actual
SDCLK frequency (i.e. Baseclock / divisor) is not reported at all:
for example, in that case, on Arasan HC, it should be 48/4=12 (MHz).

Signed-off-by: Giuseppe Cavallaro <peppe.cavallaro@st.com>
Acked-by: Adrian Hunter <adrian.hunter@intel.com>
Signed-off-by: Chris Ball <cjb@laptop.org>

3 files changed, 14 insertions, 0 deletions

diff --git a/drivers/mmc/core/debugfs.c b/drivers/mmc/core/debugfs.c
index 3923880118b6..027615d3bf3e 100644
--- a/drivers/mmc/core/debugfs.c
+++ b/drivers/mmc/core/debugfs.c
@@ -57,6 +57,8 @@ static int mmc_ios_show(struct seq_file *s, void *data)
         const char *str;
 
         seq_printf(s, "clock:\t\t%u Hz\n", ios->clock);
+        if (host->actual_clock)
+                seq_printf(s, "actual clock:\t%u Hz\n", host->actual_clock);
         seq_printf(s, "vdd:\t\t%u ", ios->vdd);
         if ((1 << ios->vdd) & MMC_VDD_165_195)
                 seq_printf(s, "(1.65 - 1.95 V)\n");
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 19ed580f2cab..a7c23118dab2 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1066,12 +1066,15 @@ static void sdhci_finish_command(struct sdhci_host *host)
 static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
 {
         int div = 0; /* Initialized for compiler warning */
+        int real_div = div, clk_mul = 1;
         u16 clk = 0;
         unsigned long timeout;
 
         if (clock == host->clock)
                 return;
 
+        host->mmc->actual_clock = 0;
+
         if (host->ops->set_clock) {
                 host->ops->set_clock(host, clock);
                 if (host->quirks & SDHCI_QUIRK_NONSTANDARD_CLOCK)
@@ -1109,6 +1112,8 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
                                  * Control register.
                                  */
                                 clk = SDHCI_PROG_CLOCK_MODE;
+                                real_div = div;
+                                clk_mul = host->clk_mul;
                                 div--;
                         }
                 } else {
@@ -1122,6 +1127,7 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
                                                 break;
                                 }
                         }
+                        real_div = div;
                         div >>= 1;
                 }
         } else {
@@ -1130,9 +1136,13 @@ static void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
                         if ((host->max_clk / div) <= clock)
                                 break;
                 }
+                real_div = div;
                 div >>= 1;
         }
 
+        if (real_div)
+                host->mmc->actual_clock = (host->max_clk * clk_mul) / real_div;
+
         clk |= (div & SDHCI_DIV_MASK) << SDHCI_DIVIDER_SHIFT;
         clk |= ((div & SDHCI_DIV_HI_MASK) >> SDHCI_DIV_MASK_LEN)
                 << SDHCI_DIVIDER_HI_SHIFT;
diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
index a3ac9c48e5de..cea064f73514 100644
--- a/include/linux/mmc/host.h
+++ b/include/linux/mmc/host.h
@@ -323,6 +323,8 @@ struct mmc_host {
         struct fault_attr       fail_mmc_request;
 #endif
 
+        unsigned int            actual_clock;   /* Actual HC clock rate */
+
         unsigned long           private[0] ____cacheline_aligned;
 };