mmc: Convert from tasklet to BH workqueue

The only generic interface to execute asynchronously in the BH context is
tasklet; however, it's marked deprecated and has some design flaws. To
replace tasklets, BH workqueue support was recently added. A BH workqueue
behaves similarly to regular workqueues except that the queued work items
are executed in the BH context.

This patch converts drivers/mmc/* from tasklet to BH workqueue.

Based on the work done by Tejun Heo <tj@kernel.org>

Tested-by: Christian Loehle <christian.loehle@arm.com>
Tested-by: Aubin Constans <aubin.constans@microchip.com>
Acked-by: Aubin Constans <aubin.constans@microchip.com>
Acked-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Reviewed-by: Christian Loehle <christian.loehle@arm.com>
Signed-off-by: Allen Pais <allen.lkml@gmail.com>
Link: https://lore.kernel.org/r/20240701100736.4001658-1-allen.lkml@gmail.com
Signed-off-by: Ulf Hansson <ulf.hansson@linaro.org>

Author: Allen Pais

drivers/mmc/host/atmel-mci.c

@@ -33,6 +33,7 @@
 #include <linux/pm.h>
 #include <linux/pm_runtime.h>
 #include <linux/pinctrl/consumer.h>
+#include <linux/workqueue.h>
 
 #include <asm/cacheflush.h>
 #include <asm/io.h>
@@ -272,12 +273,12 @@ struct atmel_mci_dma {
  *	EVENT_DATA_ERROR is pending.
  * @stop_cmdr: Value to be loaded into CMDR when the stop command is
  *	to be sent.
- * @tasklet: Tasklet running the request state machine.
+ * @bh_work: Work running the request state machine.
  * @pending_events: Bitmask of events flagged by the interrupt handler
- *	to be processed by the tasklet.
+ *	to be processed by the work.
  * @completed_events: Bitmask of events which the state machine has
  *	processed.
- * @state: Tasklet state.
+ * @state: Work state.
  * @queue: List of slots waiting for access to the controller.
  * @need_clock_update: Update the clock rate before the next request.
  * @need_reset: Reset controller before next request.
@@ -352,7 +353,7 @@ struct atmel_mci {
 	u32			data_status;
 	u32			stop_cmdr;
 
-	struct tasklet_struct	tasklet;
+	struct work_struct	bh_work;
 	unsigned long		pending_events;
 	unsigned long		completed_events;
 	enum atmel_mci_state	state;
@@ -735,7 +736,7 @@ static void atmci_timeout_timer(struct timer_list *t)
 	host->need_reset = 1;
 	host->state = STATE_END_REQUEST;
 	smp_wmb();
-	tasklet_schedule(&host->tasklet);
+	queue_work(system_bh_wq, &host->bh_work);
 }
 
 static inline unsigned int atmci_ns_to_clocks(struct atmel_mci *host,
@@ -958,7 +959,7 @@ static void atmci_pdc_complete(struct atmel_mci *host)
 
 	dev_dbg(dev, "(%s) set pending xfer complete\n", __func__);
 	atmci_set_pending(host, EVENT_XFER_COMPLETE);
-	tasklet_schedule(&host->tasklet);
+	queue_work(system_bh_wq, &host->bh_work);
 }
 
 static void atmci_dma_cleanup(struct atmel_mci *host)
@@ -972,7 +973,7 @@ static void atmci_dma_cleanup(struct atmel_mci *host)
 }
 
 /*
- * This function is called by the DMA driver from tasklet context.
+ * This function is called by the DMA driver from bh context.
  */
 static void atmci_dma_complete(void *arg)
 {
@@ -995,7 +996,7 @@ static void atmci_dma_complete(void *arg)
 	if (data) {
 		dev_dbg(dev, "(%s) set pending xfer complete\n", __func__);
 		atmci_set_pending(host, EVENT_XFER_COMPLETE);
-		tasklet_schedule(&host->tasklet);
+		queue_work(system_bh_wq, &host->bh_work);
 
 		/*
 		 * Regardless of what the documentation says, we have
@@ -1008,7 +1009,7 @@ static void atmci_dma_complete(void *arg)
 		 * haven't seen all the potential error bits yet.
 		 *
 		 * The interrupt handler will schedule a different
-		 * tasklet to finish things up when the data transfer
+		 * bh work to finish things up when the data transfer
 		 * is completely done.
 		 *
 		 * We may not complete the mmc request here anyway
@@ -1745,9 +1746,9 @@ static void atmci_detect_change(struct timer_list *t)
 	}
 }
 
-static void atmci_tasklet_func(struct tasklet_struct *t)
+static void atmci_work_func(struct work_struct *t)
 {
-	struct atmel_mci        *host = from_tasklet(host, t, tasklet);
+	struct atmel_mci        *host = from_work(host, t, bh_work);
 	struct mmc_request	*mrq = host->mrq;
 	struct mmc_data		*data = host->data;
 	struct device		*dev = host->dev;
@@ -1759,7 +1760,7 @@ static void atmci_tasklet_func(struct tasklet_struct *t)
 
 	state = host->state;
 
-	dev_vdbg(dev, "tasklet: state %u pending/completed/mask %lx/%lx/%x\n",
+	dev_vdbg(dev, "bh_work: state %u pending/completed/mask %lx/%lx/%x\n",
 		state, host->pending_events, host->completed_events,
 		atmci_readl(host, ATMCI_IMR));
 
@@ -2118,7 +2119,7 @@ static irqreturn_t atmci_interrupt(int irq, void *dev_id)
 			dev_dbg(dev, "set pending data error\n");
 			smp_wmb();
 			atmci_set_pending(host, EVENT_DATA_ERROR);
-			tasklet_schedule(&host->tasklet);
+			queue_work(system_bh_wq, &host->bh_work);
 		}
 
 		if (pending & ATMCI_TXBUFE) {
@@ -2187,7 +2188,7 @@ static irqreturn_t atmci_interrupt(int irq, void *dev_id)
 			smp_wmb();
 			dev_dbg(dev, "set pending notbusy\n");
 			atmci_set_pending(host, EVENT_NOTBUSY);
-			tasklet_schedule(&host->tasklet);
+			queue_work(system_bh_wq, &host->bh_work);
 		}
 
 		if (pending & ATMCI_NOTBUSY) {
@@ -2196,7 +2197,7 @@ static irqreturn_t atmci_interrupt(int irq, void *dev_id)
 			smp_wmb();
 			dev_dbg(dev, "set pending notbusy\n");
 			atmci_set_pending(host, EVENT_NOTBUSY);
-			tasklet_schedule(&host->tasklet);
+			queue_work(system_bh_wq, &host->bh_work);
 		}
 
 		if (pending & ATMCI_RXRDY)
@@ -2211,7 +2212,7 @@ static irqreturn_t atmci_interrupt(int irq, void *dev_id)
 			smp_wmb();
 			dev_dbg(dev, "set pending cmd rdy\n");
 			atmci_set_pending(host, EVENT_CMD_RDY);
-			tasklet_schedule(&host->tasklet);
+			queue_work(system_bh_wq, &host->bh_work);
 		}
 
 		if (pending & (ATMCI_SDIOIRQA | ATMCI_SDIOIRQB))
@@ -2487,7 +2488,7 @@ static int atmci_probe(struct platform_device *pdev)
 
 	host->mapbase = regs->start;
 
-	tasklet_setup(&host->tasklet, atmci_tasklet_func);
+	INIT_WORK(&host->bh_work, atmci_work_func);
 
 	ret = request_irq(irq, atmci_interrupt, 0, dev_name(dev), host);
 	if (ret) {

drivers/mmc/host/au1xmmc.c

@@ -42,6 +42,7 @@
 #include <linux/leds.h>
 #include <linux/mmc/host.h>
 #include <linux/slab.h>
+#include <linux/workqueue.h>
 
 #include <asm/io.h>
 #include <asm/mach-au1x00/au1000.h>
@@ -113,8 +114,8 @@ struct au1xmmc_host {
 
 	int irq;
 
-	struct tasklet_struct finish_task;
-	struct tasklet_struct data_task;
+	struct work_struct finish_bh_work;
+	struct work_struct data_bh_work;
 	struct au1xmmc_platform_data *platdata;
 	struct platform_device *pdev;
 	struct resource *ioarea;
@@ -253,9 +254,9 @@ static void au1xmmc_finish_request(struct au1xmmc_host *host)
 	mmc_request_done(host->mmc, mrq);
 }
 
-static void au1xmmc_tasklet_finish(struct tasklet_struct *t)
+static void au1xmmc_finish_bh_work(struct work_struct *t)
 {
-	struct au1xmmc_host *host = from_tasklet(host, t, finish_task);
+	struct au1xmmc_host *host = from_work(host, t, finish_bh_work);
 	au1xmmc_finish_request(host);
 }
 
@@ -363,9 +364,9 @@ static void au1xmmc_data_complete(struct au1xmmc_host *host, u32 status)
 	au1xmmc_finish_request(host);
 }
 
-static void au1xmmc_tasklet_data(struct tasklet_struct *t)
+static void au1xmmc_data_bh_work(struct work_struct *t)
 {
-	struct au1xmmc_host *host = from_tasklet(host, t, data_task);
+	struct au1xmmc_host *host = from_work(host, t, data_bh_work);
 
 	u32 status = __raw_readl(HOST_STATUS(host));
 	au1xmmc_data_complete(host, status);
@@ -425,7 +426,7 @@ static void au1xmmc_send_pio(struct au1xmmc_host *host)
 		if (host->flags & HOST_F_STOP)
 			SEND_STOP(host);
 
-		tasklet_schedule(&host->data_task);
+		queue_work(system_bh_wq, &host->data_bh_work);
 	}
 }
 
@@ -505,7 +506,7 @@ static void au1xmmc_receive_pio(struct au1xmmc_host *host)
 		if (host->flags & HOST_F_STOP)
 			SEND_STOP(host);
 
-		tasklet_schedule(&host->data_task);
+		queue_work(system_bh_wq, &host->data_bh_work);
 	}
 }
 
@@ -561,7 +562,7 @@ static void au1xmmc_cmd_complete(struct au1xmmc_host *host, u32 status)
 
 	if (!trans || cmd->error) {
 		IRQ_OFF(host, SD_CONFIG_TH | SD_CONFIG_RA | SD_CONFIG_RF);
-		tasklet_schedule(&host->finish_task);
+		queue_work(system_bh_wq, &host->finish_bh_work);
 		return;
 	}
 
@@ -797,7 +798,7 @@ static irqreturn_t au1xmmc_irq(int irq, void *dev_id)
 		IRQ_OFF(host, SD_CONFIG_NE | SD_CONFIG_TH);
 
 		/* IRQ_OFF(host, SD_CONFIG_TH | SD_CONFIG_RA | SD_CONFIG_RF); */
-		tasklet_schedule(&host->finish_task);
+		queue_work(system_bh_wq, &host->finish_bh_work);
 	}
 #if 0
 	else if (status & SD_STATUS_DD) {
@@ -806,7 +807,7 @@ static irqreturn_t au1xmmc_irq(int irq, void *dev_id)
 			au1xmmc_receive_pio(host);
 		else {
 			au1xmmc_data_complete(host, status);
-			/* tasklet_schedule(&host->data_task); */
+			/* queue_work(system_bh_wq, &host->data_bh_work); */
 		}
 	}
 #endif
@@ -854,7 +855,7 @@ static void au1xmmc_dbdma_callback(int irq, void *dev_id)
 	if (host->flags & HOST_F_STOP)
 		SEND_STOP(host);
 
-	tasklet_schedule(&host->data_task);
+	queue_work(system_bh_wq, &host->data_bh_work);
 }
 
 static int au1xmmc_dbdma_init(struct au1xmmc_host *host)
@@ -1039,9 +1040,9 @@ static int au1xmmc_probe(struct platform_device *pdev)
 	if (host->platdata)
 		mmc->caps &= ~(host->platdata->mask_host_caps);
 
-	tasklet_setup(&host->data_task, au1xmmc_tasklet_data);
+	INIT_WORK(&host->data_bh_work, au1xmmc_data_bh_work);
 
-	tasklet_setup(&host->finish_task, au1xmmc_tasklet_finish);
+	INIT_WORK(&host->finish_bh_work, au1xmmc_finish_bh_work);
 
 	if (has_dbdma()) {
 		ret = au1xmmc_dbdma_init(host);
@@ -1091,8 +1092,8 @@ static int au1xmmc_probe(struct platform_device *pdev)
 	if (host->flags & HOST_F_DBDMA)
 		au1xmmc_dbdma_shutdown(host);
 
-	tasklet_kill(&host->data_task);
-	tasklet_kill(&host->finish_task);
+	cancel_work_sync(&host->data_bh_work);
+	cancel_work_sync(&host->finish_bh_work);
 
 	if (host->platdata && host->platdata->cd_setup &&
 	    !(mmc->caps & MMC_CAP_NEEDS_POLL))
@@ -1135,8 +1136,8 @@ static void au1xmmc_remove(struct platform_device *pdev)
 		__raw_writel(0, HOST_CONFIG2(host));
 		wmb(); /* drain writebuffer */
 
-		tasklet_kill(&host->data_task);
-		tasklet_kill(&host->finish_task);
+		cancel_work_sync(&host->data_bh_work);
+		cancel_work_sync(&host->finish_bh_work);
 
 		if (host->flags & HOST_F_DBDMA)
 			au1xmmc_dbdma_shutdown(host);

drivers/mmc/host/cb710-mmc.c

@@ -493,7 +493,7 @@ static void cb710_mmc_request(struct mmc_host *mmc, struct mmc_request *mrq)
 	if (!cb710_mmc_command(mmc, mrq->cmd) && mrq->stop)
 		cb710_mmc_command(mmc, mrq->stop);
 
-	tasklet_schedule(&reader->finish_req_tasklet);
+	queue_work(system_bh_wq, &reader->finish_req_bh_work);
 }
 
 static int cb710_mmc_powerup(struct cb710_slot *slot)
@@ -646,10 +646,10 @@ static int cb710_mmc_irq_handler(struct cb710_slot *slot)
 	return 1;
 }
 
-static void cb710_mmc_finish_request_tasklet(struct tasklet_struct *t)
+static void cb710_mmc_finish_request_bh_work(struct work_struct *t)
 {
-	struct cb710_mmc_reader *reader = from_tasklet(reader, t,
-						       finish_req_tasklet);
+	struct cb710_mmc_reader *reader = from_work(reader, t,
+						       finish_req_bh_work);
 	struct mmc_request *mrq = reader->mrq;
 
 	reader->mrq = NULL;
@@ -718,8 +718,8 @@ static int cb710_mmc_init(struct platform_device *pdev)
 
 	reader = mmc_priv(mmc);
 
-	tasklet_setup(&reader->finish_req_tasklet,
-		      cb710_mmc_finish_request_tasklet);
+	INIT_WORK(&reader->finish_req_bh_work,
+			cb710_mmc_finish_request_bh_work);
 	spin_lock_init(&reader->irq_lock);
 	cb710_dump_regs(chip, CB710_DUMP_REGS_MMC);
 
@@ -763,7 +763,7 @@ static void cb710_mmc_exit(struct platform_device *pdev)
 	cb710_write_port_32(slot, CB710_MMC_CONFIG_PORT, 0);
 	cb710_write_port_16(slot, CB710_MMC_CONFIGB_PORT, 0);
 
-	tasklet_kill(&reader->finish_req_tasklet);
+	cancel_work_sync(&reader->finish_req_bh_work);
 
 	mmc_free_host(mmc);
 }

drivers/mmc/host/cb710-mmc.h

@@ -8,10 +8,11 @@
 #define LINUX_CB710_MMC_H
 
 #include <linux/cb710.h>
+#include <linux/workqueue.h>
 
 /* per-MMC-reader structure */
 struct cb710_mmc_reader {
-	struct tasklet_struct finish_req_tasklet;
+	struct work_struct finish_req_bh_work;
 	struct mmc_request *mrq;
 	spinlock_t irq_lock;
 	unsigned char last_power_mode;