[PATCH v2 1/3] spi: spi-fsl-dspi: Fix external abort on interrupt in exit paths

[Krzysztof Kozlowski]

If interrupt comes late, during probe error path or device remove (could
be triggered with CONFIG_DEBUG_SHIRQ), the interrupt handler
dspi_interrupt() will access registers with the clock being disabled.  This
leads to external abort on non-linefetch on Toradex Colibri VF50 module
(with Vybrid VF5xx):

    $ echo 4002d000.spi > /sys/devices/platform/soc/40000000.bus/4002d000.spi/driver/unbind

    Unhandled fault: external abort on non-linefetch (0x1008) at 0x8887f02c
    Internal error: : 1008 [#1] ARM
    CPU: 0 PID: 136 Comm: sh Not tainted 5.7.0-next-20200610-00009-g5c913fa0f9c5-dirty #74
    Hardware name: Freescale Vybrid VF5xx/VF6xx (Device Tree)
      (regmap_mmio_read32le) from [<8061885c>] (regmap_mmio_read+0x48/0x68)
      (regmap_mmio_read) from [<8060e3b8>] (_regmap_bus_reg_read+0x24/0x28)
      (_regmap_bus_reg_read) from [<80611c50>] (_regmap_read+0x70/0x1c0)
      (_regmap_read) from [<80611dec>] (regmap_read+0x4c/0x6c)
      (regmap_read) from [<80678ca0>] (dspi_interrupt+0x3c/0xa8)
      (dspi_interrupt) from [<8017acec>] (free_irq+0x26c/0x3cc)
      (free_irq) from [<8017dcec>] (devm_irq_release+0x1c/0x20)
      (devm_irq_release) from [<805f98ec>] (release_nodes+0x1e4/0x298)
      (release_nodes) from [<805f9ac8>] (devres_release_all+0x40/0x60)
      (devres_release_all) from [<805f5134>] (device_release_driver_internal+0x108/0x1ac)
      (device_release_driver_internal) from [<805f521c>] (device_driver_detach+0x20/0x24)

Fixes: 349ad66c0ab0 ("spi:Add Freescale DSPI driver for Vybrid VF610 platform")
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Krzysztof Kozlowski <krzk@xxxxxxxxxx>

---

This is an follow up of my other patch for I2C IMX driver [1]. Let's fix the
issues consistently.

[1] https://lore.kernel.org/lkml/1592130544-19759-2-git-send-email-krzk@xxxxxxxxxx/T/#u

Changes since v1:
1. Disable the IRQ instead of using non-devm interface.
---
 drivers/spi/spi-fsl-dspi.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/drivers/spi/spi-fsl-dspi.c b/drivers/spi/spi-fsl-dspi.c
index 58190c94561f..023e05c53b85 100644
--- a/drivers/spi/spi-fsl-dspi.c
+++ b/drivers/spi/spi-fsl-dspi.c
@@ -1400,7 +1400,7 @@ static int dspi_probe(struct platform_device *pdev)
 		ret = dspi_request_dma(dspi, res->start);
 		if (ret < 0) {
 			dev_err(&pdev->dev, "can't get dma channels\n");
-			goto out_clk_put;
+			goto disable_irq;
 		}
 	}
 
@@ -1415,11 +1415,14 @@ static int dspi_probe(struct platform_device *pdev)
 	ret = spi_register_controller(ctlr);
 	if (ret != 0) {
 		dev_err(&pdev->dev, "Problem registering DSPI ctlr\n");
-		goto out_clk_put;
+		goto disable_irq;
 	}
 
 	return ret;
 
+disable_irq:
+	if (dspi->irq > 0)
+		disable_irq(dspi->irq);
 out_clk_put:
 	clk_disable_unprepare(dspi->clk);
 out_ctlr_put:
@@ -1435,6 +1438,8 @@ static int dspi_remove(struct platform_device *pdev)
 
 	/* Disconnect from the SPI framework */
 	dspi_release_dma(dspi);
+	if (dspi->irq > 0)
+		disable_irq(dspi->irq);
 	clk_disable_unprepare(dspi->clk);
 	spi_unregister_controller(dspi->ctlr);
 
-- 
2.7.4