Re: [PATCH] ARM: mmc: bcm281xx SDHCI driver

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Thanks for the feedback.

On 13-05-08 11:35 PM, Jean-Christophe PLAGNIOL-VILLARD wrote:
On 22:55 Wed 08 May     , Christian Daudt wrote:
Add SDHCI driver for the Broadcom 281xx SoCs. Also
add bindings for it into bcm281xx dts files.
Still missing:
  - power managemement
split the dts/dtsi in an other patch
ok.
Signed-off-by: Christian Daudt <csd@xxxxxxxxxxxx>

diff --git a/arch/arm/configs/bcm_defconfig b/arch/arm/configs/bcm_defconfig
index e3bf2d6..65edf6d 100644
--- a/arch/arm/configs/bcm_defconfig
+++ b/arch/arm/configs/bcm_defconfig
@@ -78,6 +78,13 @@ CONFIG_BACKLIGHT_LCD_SUPPORT=y
  CONFIG_LCD_CLASS_DEVICE=y
  CONFIG_BACKLIGHT_CLASS_DEVICE=y
  # CONFIG_USB_SUPPORT is not set
+CONFIG_MMC=y
+CONFIG_MMC_UNSAFE_RESUME=y
+CONFIG_MMC_BLOCK_MINORS=32
+CONFIG_MMC_TEST=y
+CONFIG_MMC_SDHCI=y
+CONFIG_MMC_SDHCI_PLTFM=y
+CONFIG_MMC_SDHCI_BCM_KONA=y
  CONFIG_NEW_LEDS=y
  CONFIG_LEDS_CLASS=y
  CONFIG_LEDS_TRIGGERS=y
diff --git a/drivers/mmc/host/Kconfig b/drivers/mmc/host/Kconfig
index d88219e..e067c5a 100644
--- a/drivers/mmc/host/Kconfig
+++ b/drivers/mmc/host/Kconfig
@@ -238,6 +238,16 @@ config MMC_SDHCI_S3C_DMA

  	  YMMV.

+config MMC_SDHCI_BCM_KONA
+	tristate "SDHCI support on Broadcom KONA platform"
+	depends on ARCH_BCM && MMC_SDHCI_PLTFM
select MMC_SDHCI_PLTFM
will be better
Ok - changed it. Why is the select is better than the depends ?
+
+static int sdhci_bcm_kona_sd_reset(struct sdhci_host *host)
+{
+	unsigned int val;
+	unsigned long timeout;
+
+	/* This timeout should be sufficent for core to reset */
+	timeout = jiffies + msecs_to_jiffies(100);
+
+	/* reset the host using the top level reset */
+	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
+	val |= KONA_SDHOST_RESET;
+	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);
+
+	while (!(sdhci_readl(host, KONA_SDHOST_CORECTRL) & KONA_SDHOST_RESET)) {
+		if (time_is_before_jiffies(timeout)) {
+			pr_err("Error: sd host is stuck in reset!!!\n");
+			return -EFAULT;
+		}
+	}
+
+	/* bring the host out of reset */
+	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
+	val &= ~KONA_SDHOST_RESET;
+
+	/*
+	 * Back-to-Back register write needs a delay of 1ms at bootup (min 10uS)
+	 * Back-to-Back writes to same register needs delay when SD bus clock
+	 * is very low w.r.t AHB clock, mainly during boot-time and during card
+	 * insert-removal.
+	 */
+	udelay(1000);
really a udelay of 1ms
I'm trying to clarify on whether this is really necessary but it does seem that this is the case. I'll send a follow-up patch if I manage to get confirmation on a smaller safe number.

+	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);
+
+	return 0;
+}
+
+static void sdhci_bcm_kona_sd_init(struct sdhci_host *host)
+{
+	unsigned int val;
+
+	/* enable the interrupt from the IP core */
+	val = sdhci_readl(host, KONA_SDHOST_COREIMR);
+	val |= KONA_SDHOST_IP;
+	sdhci_writel(host, val, KONA_SDHOST_COREIMR);
+
+	/* Enable the AHB clock gating module to the host */
+	val = sdhci_readl(host, KONA_SDHOST_CORECTRL);
+	val |= KONA_SDHOST_EN;
+
+	/*
+	 * Back-to-Back register write needs a delay of 1ms at bootup (min 10uS)
+	 * Back-to-Back writes to same register needs delay when SD bus clock
+	 * is very low w.r.t AHB clock, mainly during boot-time and during card
+	 * insert-removal.
+	 */
+	udelay(1000);
ditto
see above
+	sdhci_writel(host, val, KONA_SDHOST_CORECTRL);
+}
+
+/*
+ * Software emulation of the SD card insertion/removal. Set insert=1 for insert
+ * and insert=0 for removal. The card detection is done by GPIO. For Broadcom
+ * IP to function properly the bit 0 of CORESTAT register needs to be set/reset
+ * to generate the CD IRQ handled in sdhci.c which schedules card_tasklet.
+ */
+static int sdhci_bcm_kona_sd_card_emulate(struct sdhci_host *host, int insert)
+{
+	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
+	struct sdhci_bcm_kona_dev *kona_dev = pltfm_priv->priv;
+	u32 val;
+	unsigned long flags;
+
+	/* this function can be called from various contexts including ISR */
+	spin_lock_irqsave(&host->lock, flags);
+	/* Ensure SD bus scanning to detect media change */
+	host->mmc->rescan_disable = 0;
+
+	/*
+	 * Back-to-Back register write needs a delay of min 10uS.
+	 * Back-to-Back writes to same register needs delay when SD bus clock
+	 * is very low w.r.t AHB clock, mainly during boot-time and during card
+	 * insert-removal.
+	 * We keep 20uS
+	 */
+	udelay(20);
+	val = sdhci_readl(host, KONA_SDHOST_CORESTAT);
+
+	if (insert) {
+		if (kona_dev->cfg->wp_gpio >= 0) {
gpio_is_valid
done
+			int wp_status = gpio_get_value(kona_dev->cfg->wp_gpio);
+
+			if (wp_status)
+				val |= KONA_SDHOST_WP;
+			else
+				val &= ~KONA_SDHOST_WP;
+		}
+
+		val |= KONA_SDHOST_CD_SW;
+		sdhci_writel(host, val, KONA_SDHOST_CORESTAT);
+	} else {
+		val &= ~KONA_SDHOST_CD_SW;
+		sdhci_writel(host, val, KONA_SDHOST_CORESTAT);
+	}
+	spin_unlock_irqrestore(&host->lock, flags);
+
+	return 0;
+}
+
+/*
+ * SD card detection interrupt handler
+ */
+static irqreturn_t sdhci_bcm_kona_pltfm_cd_interrupt(int irq, void *host)
+{
+	struct sdhci_pltfm_host *pltfm_priv = sdhci_priv(host);
+	struct sdhci_bcm_kona_dev *kona_dev = pltfm_priv->priv;
+
+	if (gpio_get_value_cansleep(kona_dev->cfg->cd_gpio) == 0) {
+		pr_debug("card inserted\n");
dev_dbg
done
+		sdhci_bcm_kona_sd_card_emulate(host, 1);
+	} else {
+		pr_debug("card removed\n");
ditto
done
+static struct sdhci_bcm_kona_cfg * __init sdhci_bcm_kona_parse_dt(
+			struct platform_device *pdev)
+{
+	struct sdhci_bcm_kona_cfg *cfg;
+	struct device_node *np = pdev->dev.of_node;
+	u32 temp;
+
+	if (!np)
+		return NULL;
+
+	cfg = devm_kzalloc(&pdev->dev, sizeof(*cfg), GFP_KERNEL);
+	if (!cfg) {
+		dev_err(&pdev->dev, "Can't allocate platform cfg\n");
+		return NULL;
+	}
+
+	cfg->cd_gpio = of_get_named_gpio(np, "cd-gpios", 0);
+	cfg->wp_gpio = of_get_named_gpio(np, "wp-gpios", 0);
+	if (of_get_property(np, "non-removable", NULL))
+		cfg->non_removable = 1;
use of_property_read_bool
done
+		/* Sleep for 128ms to allow debounce to stabilize */
+		msleep(SD_DETECT_GPIO_DEBOUNCE_128MS);
+		/* request irq for cd_gpio after the gpio debounce is
+		 * stabilized, otherwise, some bogus gpio interrupts might be
+		 * triggered.
+		 */
+		irq = gpio_to_irq(kona_dev->cfg->cd_gpio);
+		ret = devm_request_threaded_irq(dev,
+				irq,
+				NULL,
+				sdhci_bcm_kona_pltfm_cd_interrupt,
+				IRQF_TRIGGER_FALLING|
+				IRQF_TRIGGER_RISING |
+				IRQF_ONESHOT |
+				IRQF_NO_SUSPEND, "sdio cd", host);
+		if (ret) {
+			dev_err(kona_dev->dev,
+				"Unable to request card detection irq=%d"
+				" for gpio=%d  ret=%d\n",
put the sting of the dev_err on one line so we can grep
merged it into single line


 Thanks,
   csd


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