linux-kernel - [PATCH v2 1/2] mtd: Add flag to indicate panic

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Date:   Thu, 16 May 2019 11:45:39 -0400
From:   Kamal Dasu <kdasu.kdev@...il.com>
To:     linux-mtd@...ts.infradead.org
Cc:     bcm-kernel-feedback-list@...adcom.com,
        linux-kernel@...r.kernel.org, Kamal Dasu <kdasu.kdev@...il.com>,
        David Woodhouse <dwmw2@...radead.org>,
        Brian Norris <computersforpeace@...il.com>,
        Marek Vasut <marek.vasut@...il.com>,
        Miquel Raynal <miquel.raynal@...tlin.com>,
        Richard Weinberger <richard@....at>,
        Vignesh Raghavendra <vigneshr@...com>
Subject: [PATCH v2 1/2] mtd: Add flag to indicate panic_write

Added a flag to indicate a panic_write so that low level drivers can
use it to take required action where applicable, to ensure oops data
gets written to assigned mtd device.

Signed-off-by: Kamal Dasu <kdasu.kdev@...il.com>
---
 drivers/mtd/mtdcore.c                    |  3 ++
 drivers/mtd/nand/raw/brcmnand/brcmnand.c | 49 ++++++++++++++++++++++++++++++--
 include/linux/mtd/mtd.h                  |  6 ++++
 3 files changed, 55 insertions(+), 3 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 76b4264..a83decd 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -1138,6 +1138,9 @@ int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
 		return -EROFS;
 	if (!len)
 		return 0;
+	if (!mtd->oops_panic_write)
+		mtd->oops_panic_write = true;
+
 	return mtd->_panic_write(mtd, to, len, retlen, buf);
 }
 EXPORT_SYMBOL_GPL(mtd_panic_write);
diff --git a/drivers/mtd/nand/raw/brcmnand/brcmnand.c b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
index ce0b8ff..a30a7f0 100644
--- a/drivers/mtd/nand/raw/brcmnand/brcmnand.c
+++ b/drivers/mtd/nand/raw/brcmnand/brcmnand.c
@@ -159,6 +159,7 @@ struct brcmnand_controller {
 	u32			nand_cs_nand_xor;
 	u32			corr_stat_threshold;
 	u32			flash_dma_mode;
+	bool			pio_poll_mode;
 };
 
 struct brcmnand_cfg {
@@ -823,6 +824,21 @@ static inline bool has_flash_dma(struct brcmnand_controller *ctrl)
 	return ctrl->flash_dma_base;
 }
 
+static inline void disable_ctrl_irqs(struct brcmnand_controller *ctrl)
+{
+	if (ctrl->pio_poll_mode)
+		return;
+
+	if (has_flash_dma(ctrl)) {
+		ctrl->flash_dma_base = 0;
+		disable_irq(ctrl->dma_irq);
+	}
+
+	disable_irq(ctrl->irq);
+
+	ctrl->pio_poll_mode = true;
+}
+
 static inline bool flash_dma_buf_ok(const void *buf)
 {
 	return buf && !is_vmalloc_addr(buf) &&
@@ -1237,15 +1253,42 @@ static void brcmnand_cmd_ctrl(struct nand_chip *chip, int dat,
 	/* intentionally left blank */
 }
 
+static bool brcmstb_nand_wait_for_completion(struct nand_chip *chip)
+{
+	struct brcmnand_host *host = nand_get_controller_data(chip);
+	struct brcmnand_controller *ctrl = host->ctrl;
+	struct mtd_info *mtd = nand_to_mtd(chip);
+	bool err = false;
+	int sts;
+
+	if (mtd->oops_panic_write) {
+		/* switch to interrupt polling and PIO mode */
+		disable_ctrl_irqs(ctrl);
+		sts = bcmnand_ctrl_poll_status(ctrl, NAND_CTRL_RDY,
+					       NAND_CTRL_RDY, 0);
+		err = (sts < 0) ? true : false;
+	} else {
+		unsigned long timeo = msecs_to_jiffies(
+						NAND_POLL_STATUS_TIMEOUT_MS);
+		/* wait for completion interrupt */
+		sts = wait_for_completion_timeout(&ctrl->done, timeo);
+		err = (sts <= 0) ? true : false;
+	}
+
+	return err;
+}
+
 static int brcmnand_waitfunc(struct nand_chip *chip)
 {
 	struct brcmnand_host *host = nand_get_controller_data(chip);
 	struct brcmnand_controller *ctrl = host->ctrl;
-	unsigned long timeo = msecs_to_jiffies(100);
+	bool err = false;
 
 	dev_dbg(ctrl->dev, "wait on native cmd %d\n", ctrl->cmd_pending);
-	if (ctrl->cmd_pending &&
-			wait_for_completion_timeout(&ctrl->done, timeo) <= 0) {
+	if (ctrl->cmd_pending)
+		err = brcmstb_nand_wait_for_completion(chip);
+
+	if (err) {
 		u32 cmd = brcmnand_read_reg(ctrl, BRCMNAND_CMD_START)
 					>> brcmnand_cmd_shift(ctrl);
 
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 677768b..791c34d 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -330,6 +330,12 @@ struct mtd_info {
 	int (*_get_device) (struct mtd_info *mtd);
 	void (*_put_device) (struct mtd_info *mtd);
 
+	/*
+	 * flag indicates a panic write, low level drivers can take appropriate
+	 * action if required to ensure writes go through
+	 */
+	bool oops_panic_write;
+
 	struct notifier_block reboot_notifier;  /* default mode before reboot */
 
 	/* ECC status information */
-- 
1.9.0.138.g2de3478