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From: Romain Naour <romain.naour@smile.fr>
To: linux-kernel@vger.kernel.org,
	linux-omap@vger.kernel.org
Cc: tony@atomide.com,
	lgirdwood@gmail.com,
	broonie@kernel.org,
	Romain Naour <romain.naour@skf.com>,
	Yoann Congal <yoann.congal@smile.fr>
Subject: [PATCH v2] regulator: ti-abb: don't use devm_platform_ioremap_resource_byname for shared interrupt register
Date: Tue, 23 Jan 2024 12:14:56 +0100
Message-ID: <20240123111456.739381-1-romain.naour@smile.fr>
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From: Romain Naour <romain.naour@skf.com>

We can't use devm_platform_ioremap_resource_byname() to remap the
interrupt register that can be shared between
regulator-abb-{ivahd,dspeve,gpu} drivers instances.

The combined helper introduce a call to devm_request_mem_region() that
creates a new busy resource region on PRM_IRQSTATUS_MPU register
(0x4ae06010). The first devm_request_mem_region() call succeeds for
regulator-abb-ivahd but fails for the two other regulator-abb-dspeve
and regulator-abb-gpu.

  # cat /proc/iomem | grep -i 4ae06
  4ae06010-4ae06013 : 4ae07e34.regulator-abb-ivahd int-address
  4ae06014-4ae06017 : 4ae07ddc.regulator-abb-mpu int-address

regulator-abb-dspeve and regulator-abb-gpu are missing due to
devm_request_mem_region() failure (EBUSY):

  [    1.326660] ti_abb 4ae07e30.regulator-abb-dspeve: can't request region for resource [mem 0x4ae06010-0x4ae06013]
  [    1.326660] ti_abb: probe of 4ae07e30.regulator-abb-dspeve failed with error -16
  [    1.327239] ti_abb 4ae07de4.regulator-abb-gpu: can't request region for resource [mem 0x4ae06010-0x4ae06013]
  [    1.327270] ti_abb: probe of 4ae07de4.regulator-abb-gpu failed with error -16

From arm/boot/dts/dra7.dtsi:

The abb_mpu is the only instance using its own interrupt register:
  (0x4ae06014) PRM_IRQSTATUS_MPU_2, ABB_MPU_DONE_ST (bit 7)

The other tree instances (abb_ivahd, abb_dspeve, abb_gpu) share
PRM_IRQSTATUS_MPU register (0x4ae06010) but use different bits
ABB_IVA_DONE_ST (bit 30), ABB_DSPEVE_DONE_ST( bit 29) and
ABB_GPU_DONE_ST (but 28).

The commit b36c6b1887ff ("regulator: ti-abb: Make use of the helper
function devm_ioremap related") overlooked the following comment
implicitly explaining why devm_ioremap() is used in this case:

  /*
   * We may have shared interrupt register offsets which are
   * write-1-to-clear between domains ensuring exclusivity.
   */

Fixes and partially reverts commit b36c6b1887ff ("regulator: ti-abb:
Make use of the helper function devm_ioremap related").

Improve the existing comment to avoid further conversion to
devm_platform_ioremap_resource_byname().

Fixes: b36c6b1887ff ("regulator: ti-abb: Make use of the helper function devm_ioremap related")
Signed-off-by: Romain Naour <romain.naour@skf.com>
Reviewed-by: Yoann Congal <yoann.congal@smile.fr>
---
v2: improve commit log and update comment preventing further conversion
to devm_platform_ioremap_resource_byname().
---
 drivers/regulator/ti-abb-regulator.c | 22 +++++++++++++++++++---
 1 file changed, 19 insertions(+), 3 deletions(-)

diff --git a/drivers/regulator/ti-abb-regulator.c b/drivers/regulator/ti-abb-regulator.c
index f48214e2c3b4..04133510e5af 100644
--- a/drivers/regulator/ti-abb-regulator.c
+++ b/drivers/regulator/ti-abb-regulator.c
@@ -726,9 +726,25 @@ static int ti_abb_probe(struct platform_device *pdev)
 			return PTR_ERR(abb->setup_reg);
 	}
 
-	abb->int_base = devm_platform_ioremap_resource_byname(pdev, "int-address");
-	if (IS_ERR(abb->int_base))
-		return PTR_ERR(abb->int_base);
+	pname = "int-address";
+	res = platform_get_resource_byname(pdev, IORESOURCE_MEM, pname);
+	if (!res) {
+		dev_err(dev, "Missing '%s' IO resource\n", pname);
+		return -ENODEV;
+	}
+	/*
+	 * The MPU interrupt status register (PRM_IRQSTATUS_MPU) is
+	 * shared between regulator-abb-{ivahd,dspeve,gpu} driver
+	 * instances. Therefore use devm_ioremap() rather than
+	 * devm_platform_ioremap_resource_byname() to avoid busy
+	 * resource region conflicts.
+	 */
+	abb->int_base = devm_ioremap(dev, res->start,
+					     resource_size(res));
+	if (!abb->int_base) {
+		dev_err(dev, "Unable to map '%s'\n", pname);
+		return -ENOMEM;
+	}
 
 	/* Map Optional resources */
 	pname = "efuse-address";
-- 
2.43.0