[RFC PATCH v1 2/2] scsi: ufs: ufs-exynos: implement exynos isr

Kiwoong Kim
2021-08-06T06:49:39Z

Based on some events in the real world, I implement
this to block the host's working in some abnormal
conditions using an vendor specific interrupt for
cases that some contexts of a pending request in the
host isn't the same with those of its corresponding UPIUs
if they should have been the same exactly.

Signed-off-by: Kiwoong Kim <kwmad.kim@samsung.com>
---
drivers/scsi/ufs/ufs-exynos.c | 78 +++++++++++++++++++++++++++++------
1 file changed, 66 insertions(+), 12 deletions(-)

diff --git a/drivers/scsi/ufs/ufs-exynos.c b/drivers/scsi/ufs/ufs-exynos.c
index cf46d6f86e0e..2cfe959e05b6 100644
--- a/drivers/scsi/ufs/ufs-exynos.c
+++ b/drivers/scsi/ufs/ufs-exynos.c
@@ -31,6 +31,8 @@
#define HCI_RXPRDT_ENTRY_SIZE 0x04
#define HCI_1US_TO_CNT_VAL 0x0C
#define CNT_VAL_1US_MASK 0x3FF
+#define VENDOR_SPECIFIC_IS 0x38
+#define VENDOR_SPECIFIC_IE 0x3C
#define HCI_UTRL_NEXUS_TYPE 0x40
#define HCI_UTMRL_NEXUS_TYPE 0x44
#define HCI_SW_RST 0x50
@@ -74,6 +76,18 @@
UIC_TRANSPORT_NO_CONNECTION_RX |\
UIC_TRANSPORT_BAD_TC)

+enum exynos_ufs_vs_interrupt {
+ /*
+ * This occurs when information of a pending request isn't
+ * the same with incoming UPIU for the request. For example,
+ * if UFS driver rings with task tag #1, subsequential UPIUs
+ * for this must have one as the value of task tag. But if
+ * it's corrutped until the host receives it or incoming UPIUs
+ * has an unexpected value for task tag, this raises.
+ */
+ RX_UPIU_HIT_ERROR = 1 << 19,
+};
+
enum {
UNIPRO_L1_5 = 0,/* PHY Adapter */
UNIPRO_L2, /* Data Link */
@@ -996,6 +1010,10 @@ static int exynos_ufs_init(struct ufs_hba *hba)
goto out;
exynos_ufs_specify_phy_time_attr(ufs);
exynos_ufs_config_smu(ufs);
+
+ /* enable vendor interrupts */
+ hci_writel(ufs, VENDOR_SPECIFIC_IE, RX_UPIU_HIT_ERROR);
+
return 0;

phy_off:
@@ -1005,26 +1023,33 @@ static int exynos_ufs_init(struct ufs_hba *hba)
return ret;
}

-static int exynos_ufs_host_reset(struct ufs_hba *hba)
+static int exynos_ufs_host_reset(struct exynos_ufs *ufs)
{
- struct exynos_ufs *ufs = ufshcd_get_variant(hba);
unsigned long timeout = jiffies + msecs_to_jiffies(1);
- u32 val;
- int ret = 0;
-
- exynos_ufs_disable_auto_ctrl_hcc_save(ufs, &val);

+ /* host reset */
hci_writel(ufs, UFS_SW_RST_MASK, HCI_SW_RST);
-
do {
if (!(hci_readl(ufs, HCI_SW_RST) & UFS_SW_RST_MASK))
- goto out;
+ return 0;
} while (time_before(jiffies, timeout));

- dev_err(hba->dev, "timeout host sw-reset\n");
- ret = -ETIMEDOUT;
+ pr_err("timeout host sw-reset\n");
+ return -ETIMEDOUT;
+}
+
+static int exynos_ufs_host_init(struct ufs_hba *hba)
+{
+ struct exynos_ufs *ufs = ufshcd_get_variant(hba);
+ u32 val;
+ int ret;
+
+ exynos_ufs_disable_auto_ctrl_hcc_save(ufs, &val);
+
+ ret = exynos_ufs_host_reset(ufs);
+ if (ret)
+ return ret;

-out:
exynos_ufs_auto_ctrl_hcc_restore(ufs, &val);
return ret;
}
@@ -1110,7 +1135,7 @@ static int exynos_ufs_hce_enable_notify(struct ufs_hba *hba,

switch (status) {
case PRE_CHANGE:
- ret = exynos_ufs_host_reset(hba);
+ ret = exynos_ufs_host_init(hba);
if (ret)
return ret;
exynos_ufs_dev_hw_reset(hba);
@@ -1198,6 +1223,34 @@ static int exynos_ufs_resume(struct ufs_hba *hba, enum ufs_pm_op pm_op)
return 0;
}

+static irqreturn_t exynos_ufs_isr(struct ufs_hba *hba, int *res)
+{
+ struct exynos_ufs *ufs = ufshcd_get_variant(hba);
+ u32 status;
+
+ status = hci_readl(ufs, VENDOR_SPECIFIC_IS);
+ hci_writel(ufs, status, VENDOR_SPECIFIC_IS);
+ /*
+ * If host doesn't guarantee integrity of UTP transmission,
+ * it needs to be reset immediately to make it unable to
+ * proceed requests. Because w/o this, if UTP functions
+ * in host doesn't work properly for such system power margins,
+ * DATA IN from broken devices or whatever in the real world,
+ * some unexpected events could happen, such as tranferring
+ * a broken DATA IN to a device. It could be various types of
+ * problems on the level of file system. In this case, I think
+ * blocking the host's functionality is the best strategy.
+ * Perhaps, if its root cause is temporary, system could recover.
+ */
+ if (status & RX_UPIU_HIT_ERROR) {
+ pr_err("%s: status: 0x%08x\n", __func__, status);
+ exynos_ufs_host_reset(ufs);
+ *res = 1;
+ return IRQ_HANDLED;
+ }
+ return IRQ_NONE;
+}
+
static struct ufs_hba_variant_ops ufs_hba_exynos_ops = {
.name = "exynos_ufs",
.init = exynos_ufs_init,
@@ -1209,6 +1262,7 @@ static struct ufs_hba_variant_ops ufs_hba_exynos_ops = {
.hibern8_notify = exynos_ufs_hibern8_notify,
.suspend = exynos_ufs_suspend,
.resume = exynos_ufs_resume,
+ .intr = exynos_ufs_isr,
};

static int exynos_ufs_probe(struct platform_device *pdev)
--
2.31.1