[PATCH v2 2/5] mmc: sdhci-pxav3: enable usage of DAT3 pin as HW card detect
Marcin Wojtas
mw at semihalf.com
Thu Oct 8 18:03:52 PDT 2015
Marvell Armada 38x SDHCI controller enable using DAT3 pin as a hardware
card detection. According to the SD sdandard this signal can be used for
this purpose combined with a pull-up resistor, implying inverted (active
low) polarization of a card detect. MMC standard does not support this
feature and does not operate with such connectivity of DAT3.
When using DAT3-based detection Armada 38x SDIO IP expects its internal
clock to be always on, which had to be ensured twofold:
- Each time controller is reset by updating appropriate registers. On the
occasion of adding new register @0x104, register @0x100 name is modified
in order to the be aligned with Armada 38x documentation.
- Leaving the clock enabled despite power-down. For this purpose a new
quirk had to be added to SDHCI subsystem - SDHCI_QUIRK2_KEEP_INT_CLK_ON.
In addition to the changes above this commit adds a new property to Armada
38x SDHCI node ('dat3-cd') with an according binding documentation update.
Signed-off-by: Marcin Wojtas <mw at semihalf.com>
---
.../devicetree/bindings/mmc/sdhci-pxa.txt | 5 +++
drivers/mmc/host/sdhci-pxav3.c | 38 ++++++++++++++++++++--
drivers/mmc/host/sdhci.c | 5 ++-
drivers/mmc/host/sdhci.h | 3 ++
4 files changed, 47 insertions(+), 4 deletions(-)
diff --git a/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt b/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt
index 3d1b449..ffd6b14 100644
--- a/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt
+++ b/Documentation/devicetree/bindings/mmc/sdhci-pxa.txt
@@ -23,6 +23,11 @@ Required properties:
Optional properties:
- mrvl,clk-delay-cycles: Specify a number of cycles to delay for tuning.
+- dat3-cd: use DAT3 pin as hardware card detect - option available for
+ "marvell,armada-380-sdhci" only. The detection is supposed to work with
+ active high polarity, which implies usage of "cd-inverted" property.
+ Note that according to the specifications DAT3-based card detection can be
+ used with SD cards only. MMC standard doesn't support this feature.
Example:
diff --git a/drivers/mmc/host/sdhci-pxav3.c b/drivers/mmc/host/sdhci-pxav3.c
index 76b9a70..352c5eb 100644
--- a/drivers/mmc/host/sdhci-pxav3.c
+++ b/drivers/mmc/host/sdhci-pxav3.c
@@ -46,10 +46,14 @@
#define SDCLK_DELAY_SHIFT 9
#define SDCLK_DELAY_MASK 0x1f
-#define SD_CFG_FIFO_PARAM 0x100
+#define SD_EXTRA_PARAM_REG 0x100
#define SDCFG_GEN_PAD_CLK_ON (1<<6)
#define SDCFG_GEN_PAD_CLK_CNT_MASK 0xFF
#define SDCFG_GEN_PAD_CLK_CNT_SHIFT 24
+#define SD_FIFO_PARAM_REG 0x104
+#define SD_USE_DAT3 BIT(7)
+#define SD_OVRRD_CLK_OEN BIT(11)
+#define SD_FORCE_CLK_ON BIT(12)
#define SD_SPI_MODE 0x108
#define SD_CE_ATA_1 0x10C
@@ -163,6 +167,15 @@ static int armada_38x_quirks(struct platform_device *pdev,
}
host->caps1 &= ~(SDHCI_SUPPORT_SDR104 | SDHCI_USE_SDR50_TUNING);
+ /*
+ * The interface clock enable is also used as control
+ * for the A38x SDIO IP, so it can't be powered down
+ * when using HW-based card detection.
+ */
+ if (of_property_read_bool(np, "dat3-cd") &&
+ !of_property_read_bool(np, "broken-cd"))
+ host->quirks2 |= SDHCI_QUIRK2_KEEP_INT_CLK_ON;
+
return 0;
}
@@ -170,6 +183,8 @@ static void pxav3_reset(struct sdhci_host *host, u8 mask)
{
struct platform_device *pdev = to_platform_device(mmc_dev(host->mmc));
struct sdhci_pxa_platdata *pdata = pdev->dev.platform_data;
+ struct device_node *np = pdev->dev.of_node;
+ u32 reg_val;
sdhci_reset(host, mask);
@@ -187,6 +202,22 @@ static void pxav3_reset(struct sdhci_host *host, u8 mask)
tmp |= SDCLK_SEL;
writew(tmp, host->ioaddr + SD_CLOCK_BURST_SIZE_SETUP);
}
+
+ if (of_device_is_compatible(np, "marvell,armada-380-sdhci") &&
+ host->quirks2 & SDHCI_QUIRK2_KEEP_INT_CLK_ON) {
+ reg_val = sdhci_readl(host, SD_FIFO_PARAM_REG);
+ reg_val |= SD_USE_DAT3 | SD_OVRRD_CLK_OEN |
+ SD_FORCE_CLK_ON;
+ sdhci_writel(host, reg_val, SD_FIFO_PARAM_REG);
+
+ /*
+ * For HW detection based on DAT3 pin keep internal
+ * clk switched on after controller reset.
+ */
+ reg_val = sdhci_readl(host, SDHCI_CLOCK_CONTROL);
+ reg_val |= SDHCI_CLOCK_INT_EN;
+ sdhci_writel(host, reg_val, SDHCI_CLOCK_CONTROL);
+ }
}
}
@@ -214,9 +245,9 @@ static void pxav3_gen_init_74_clocks(struct sdhci_host *host, u8 power_mode)
writew(tmp, host->ioaddr + SD_CE_ATA_2);
/* start sending the 74 clocks */
- tmp = readw(host->ioaddr + SD_CFG_FIFO_PARAM);
+ tmp = readw(host->ioaddr + SD_EXTRA_PARAM_REG);
tmp |= SDCFG_GEN_PAD_CLK_ON;
- writew(tmp, host->ioaddr + SD_CFG_FIFO_PARAM);
+ writew(tmp, host->ioaddr + SD_EXTRA_PARAM_REG);
/* slowest speed is about 100KHz or 10usec per clock */
udelay(740);
@@ -410,6 +441,7 @@ static int sdhci_pxav3_probe(struct platform_device *pdev)
sdhci_get_of_property(pdev);
pdata = pxav3_get_mmc_pdata(dev);
pdev->dev.platform_data = pdata;
+
} else if (pdata) {
/* on-chip device */
if (pdata->flags & PXA_FLAG_CARD_PERMANENT)
diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
index 64b7fdb..cfed695 100644
--- a/drivers/mmc/host/sdhci.c
+++ b/drivers/mmc/host/sdhci.c
@@ -1159,7 +1159,10 @@ void sdhci_set_clock(struct sdhci_host *host, unsigned int clock)
host->mmc->actual_clock = 0;
- sdhci_writew(host, 0, SDHCI_CLOCK_CONTROL);
+ /* Some controllers need to keep internal clk always enabled */
+ if (host->quirks2 & SDHCI_QUIRK2_KEEP_INT_CLK_ON)
+ clk = SDHCI_CLOCK_INT_EN;
+ sdhci_writew(host, clk, SDHCI_CLOCK_CONTROL);
if (clock == 0)
return;
diff --git a/drivers/mmc/host/sdhci.h b/drivers/mmc/host/sdhci.h
index 7c02ff4..c751b78 100644
--- a/drivers/mmc/host/sdhci.h
+++ b/drivers/mmc/host/sdhci.h
@@ -412,6 +412,9 @@ struct sdhci_host {
#define SDHCI_QUIRK2_ACMD23_BROKEN (1<<14)
/* Broken Clock divider zero in controller */
#define SDHCI_QUIRK2_CLOCK_DIV_ZERO_BROKEN (1<<15)
+/* Do not disable internal clk on power-off */
+#define SDHCI_QUIRK2_KEEP_INT_CLK_ON (1<<16)
+
int irq; /* Device IRQ */
void __iomem *ioaddr; /* Mapped address */
--
1.8.3.1
More information about the linux-arm-kernel
mailing list