mmc: mmci: add threaded irq to abort DPSM of non-functional state

The stm32_sdmmc variant has build-in support for datatimeout for R1B
requests. If a corresponding IRQ is raised, this triggers the DPSM to stay
busy and remains in a non-functional state. Only a reset can bring it back
to a functional state.

Because a reset must be issued from non-atomic context, let's defer this to
be managed from a threaded IRQ handler. Besides the reset, the threaded
handler also calls mmc_request_done(), to finally complete the request.

Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
Link: https://lore.kernel.org/r/20191211133934.16932-1-ludovic.Barre@st.com
[Ulf: A few minor updates to the changelog/comments]
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

diff --git a/drivers/mmc/host/mmci.c b/drivers/mmc/host/mmci.c
index 39bc4d9..b2b6daf 100644 (file)
--- a/drivers/mmc/host/mmci.c
+++ b/drivers/mmc/host/mmci.c
@@ -1321,6 +1321,7 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
        } else if (host->variant->busy_timeout && busy_resp &&
                   status & MCI_DATATIMEOUT) {
                cmd->error = -ETIMEDOUT;
+               host->irq_action = IRQ_WAKE_THREAD;
        } else {
                cmd->resp[0] = readl(base + MMCIRESPONSE0);
                cmd->resp[1] = readl(base + MMCIRESPONSE1);
@@ -1339,7 +1340,10 @@ mmci_cmd_irq(struct mmci_host *host, struct mmc_command *cmd,
                                return;
                        }
                }
-               mmci_request_end(host, host->mrq);
+
+               if (host->irq_action != IRQ_WAKE_THREAD)
+                       mmci_request_end(host, host->mrq);
+
        } else if (sbc) {
                mmci_start_command(host, host->mrq->cmd, 0);
        } else if (!host->variant->datactrl_first &&
@@ -1532,9 +1536,9 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
 {
        struct mmci_host *host = dev_id;
        u32 status;
-       int ret = 0;
 
        spin_lock(&host->lock);
+       host->irq_action = IRQ_HANDLED;
 
        do {
                status = readl(host->base + MMCISTATUS);
@@ -1574,12 +1578,41 @@ static irqreturn_t mmci_irq(int irq, void *dev_id)
                if (host->variant->busy_detect_flag)
                        status &= ~host->variant->busy_detect_flag;
 
-               ret = 1;
        } while (status);
 
        spin_unlock(&host->lock);
 
-       return IRQ_RETVAL(ret);
+       return host->irq_action;
+}
+
+/*
+ * mmci_irq_thread() - A threaded IRQ handler that manages a reset of the HW.
+ *
+ * A reset is needed for some variants, where a datatimeout for a R1B request
+ * causes the DPSM to stay busy (non-functional).
+ */
+static irqreturn_t mmci_irq_thread(int irq, void *dev_id)
+{
+       struct mmci_host *host = dev_id;
+       unsigned long flags;
+
+       if (host->rst) {
+               reset_control_assert(host->rst);
+               udelay(2);
+               reset_control_deassert(host->rst);
+       }
+
+       spin_lock_irqsave(&host->lock, flags);
+       writel(host->clk_reg, host->base + MMCICLOCK);
+       writel(host->pwr_reg, host->base + MMCIPOWER);
+       writel(MCI_IRQENABLE | host->variant->start_err,
+              host->base + MMCIMASK0);
+
+       host->irq_action = IRQ_HANDLED;
+       mmci_request_end(host, host->mrq);
+       spin_unlock_irqrestore(&host->lock, flags);
+
+       return host->irq_action;
 }
 
 static void mmci_request(struct mmc_host *mmc, struct mmc_request *mrq)
@@ -2063,8 +2096,9 @@ static int mmci_probe(struct amba_device *dev,
                        goto clk_disable;
        }
 
-       ret = devm_request_irq(&dev->dev, dev->irq[0], mmci_irq, IRQF_SHARED,
-                       DRIVER_NAME " (cmd)", host);
+       ret = devm_request_threaded_irq(&dev->dev, dev->irq[0], mmci_irq,
+                                       mmci_irq_thread, IRQF_SHARED,
+                                       DRIVER_NAME " (cmd)", host);
        if (ret)
                goto clk_disable;
 

diff --git a/drivers/mmc/host/mmci.h b/drivers/mmc/host/mmci.h
index 12d4ed8..be6cd1d 100644 (file)
--- a/drivers/mmc/host/mmci.h
+++ b/drivers/mmc/host/mmci.h
@@ -411,6 +411,7 @@ struct mmci_host {
 
        struct timer_list       timer;
        unsigned int            oldstat;
+       u32                     irq_action;
 
        /* pio stuff */
        struct sg_mapping_iter  sg_miter;