[PATCH] debug-add-glamo-drive-strength-module-param.patch

[Andy Green]

Suggested-by: Werner Almesberger <werner at openmoko.org>

This patch allows users to control two additional settings
in Glamo MCI driver from kernel commandline or module
parameters.


First is Glamo drive strength on SD IOs including CLK.
This ranges from 0 (weakest) to 3 (strongest).

echo 0 > /sys/module/glamo_mci/parameters/sd_drive

(Changes to this take effect on next SD Card transaction)

or, from kernel commandline

glamo_mci.sd_drive=0

On tests here with 0 strength, communication to SD card
(shipped 512MB Sandisk) seemed fine, and a dd of 10MB
urandom had the same md5 when written to cache as after
a reboot.  I set the default to 2.


Second is whether we allow SD_CLK when the SD interface
is idle.

# stop the clock when we are idle (default)
echo 0 > /sys/module/glamo_mci/parameters/sd_idleclk

# run the SD clock all the time
echo 1 > /sys/module/glamo_mci/parameters/sd_idleclk

(changes take effect on next SD Card transaction)

>From kernel commandline, eg:

glamo_mci.sd_idleclk=1

Normally you don't want to run the SD Clock all the time.


Signed-off-by: Andy Green <andy at openmoko.com>
---

 drivers/mfd/glamo/glamo-mci.c |   59 +++++++++++++++++++++++++++++++----------
 1 files changed, 45 insertions(+), 14 deletions(-)

diff --git a/drivers/mfd/glamo/glamo-mci.c b/drivers/mfd/glamo/glamo-mci.c
index 2318e6f..6585821 100644
--- a/drivers/mfd/glamo/glamo-mci.c
+++ b/drivers/mfd/glamo/glamo-mci.c
@@ -56,6 +56,32 @@ static void glamo_mci_send_request(struct mmc_host *mmc);
 static int sd_max_clk = 50000000 / 3;
 module_param(sd_max_clk, int, 0644);
 
+/*
+ * SD Signal drive strength
+ *
+ * you can override this on kernel commandline using
+ *
+ *   glamo_mci.sd_drive=0
+ *
+ * for example
+ */
+
+static int sd_drive = 2;
+module_param(sd_drive, int, 0644);
+
+/*
+ * SD allow SD clock to run while idle
+ *
+ * you can override this on kernel commandline using
+ *
+ *   glamo_mci.sd_idleclk=0
+ *
+ * for example
+ */
+
+static int sd_idleclk = 0; /* disallow idle clock by default */
+module_param(sd_idleclk, int, 0644);
+
 
 
 unsigned char CRC7(u8 * pu8, int cnt)
@@ -239,7 +265,9 @@ static int __glamo_mci_set_card_clock(struct glamo_mci_host *host, int freq,
 		if (division)
 			*division = 0xff;
 
-		__glamo_mci_fix_card_div(host, -1); /* clock off */
+		if (!sd_idleclk)
+			/* clock off */
+			__glamo_mci_fix_card_div(host, -1);
 	}
 
 	return real_rate;
@@ -294,8 +322,9 @@ static void glamo_mci_irq(unsigned int irq, struct irq_desc *desc)
 		host->cmd_is_stop = 0;
 	}
 
-	/* clock off */
-	__glamo_mci_fix_card_div(host, -1);
+	if (!sd_idleclk)
+		/* clock off */
+		__glamo_mci_fix_card_div(host, -1);
 
 done:
 	host->complete_what = COMPLETION_NONE;
@@ -428,12 +457,10 @@ static int glamo_mci_send_command(struct glamo_mci_host *host,
 	} else
 		writew(0xfff, host->base + GLAMO_REG_MMC_TIMEOUT);
 
-	/* Generate interrupt on txfer; drive strength max */
-	writew_dly((readw_dly(host->base + GLAMO_REG_MMC_BASIC) & 0xfe) |
+	/* Generate interrupt on txfer */
+	writew_dly((readw_dly(host->base + GLAMO_REG_MMC_BASIC) & 0x3e) |
 		   0x0800 | GLAMO_BASIC_MMC_NO_CLK_RD_WAIT |
-		   GLAMO_BASIC_MMC_EN_COMPL_INT |
-		   GLAMO_BASIC_MMC_EN_DR_STR0 |
-		   GLAMO_BASIC_MMC_EN_DR_STR1,
+		   GLAMO_BASIC_MMC_EN_COMPL_INT | (sd_drive << 6),
 		   host->base + GLAMO_REG_MMC_BASIC);
 
 	/* send the command out on the wire */
@@ -620,8 +647,9 @@ done:
 	host->mrq = NULL;
 	mmc_request_done(host->mmc, cmd->mrq);
 bail:
-	/* stop the clock to card */
-	__glamo_mci_fix_card_div(host, -1);
+	if (!sd_idleclk)
+		/* stop the clock to card */
+		__glamo_mci_fix_card_div(host, -1);
 }
 
 static void glamo_mci_request(struct mmc_host *mmc, struct mmc_request *mrq)
@@ -687,8 +715,9 @@ static void glamo_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	host->real_rate = __glamo_mci_set_card_clock(host, ios->clock, &div);
 	host->clk_div = div;
 
-	/* stop the clock to card, because we are idle until transfer */
-	__glamo_mci_fix_card_div(host, -1);
+	if (!sd_idleclk)
+		/* stop the clock to card, because we are idle until transfer */
+		__glamo_mci_fix_card_div(host, -1);
 
 	if ((ios->power_mode == MMC_POWER_ON) ||
 	    (ios->power_mode == MMC_POWER_UP)) {
@@ -705,8 +734,10 @@ static void glamo_mci_set_ios(struct mmc_host *mmc, struct mmc_ios *ios)
 	if (host->bus_width == MMC_BUS_WIDTH_4)
 		n = GLAMO_BASIC_MMC_EN_4BIT_DATA;
 	writew_dly((readw_dly(host->base + GLAMO_REG_MMC_BASIC) &
-					  (~GLAMO_BASIC_MMC_EN_4BIT_DATA)) | n,
-					      host->base + GLAMO_REG_MMC_BASIC);
+					  (~(GLAMO_BASIC_MMC_EN_4BIT_DATA |
+					     GLAMO_BASIC_MMC_EN_DR_STR0 |
+					     GLAMO_BASIC_MMC_EN_DR_STR1))) | n |
+			       sd_drive << 6, host->base + GLAMO_REG_MMC_BASIC);
 }