linux-kernel - [PATCH 1/4] w1: ds1wm: Fix check for resource size

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Date:   Thu, 30 Jun 2022 13:26:48 +0200
From:   Julian Haller <julian.haller@....ms.philips.com>
To:     linux-kernel@...r.kernel.org
Cc:     julian.haller@...lips.com, zbr@...emap.net
Subject: [PATCH 1/4] w1: ds1wm: Fix check for resource size

From: Julian Haller <julian.haller@...lips.com>

Commit 242b476f821b ("w1: ds1wm: fix register offset (bus shift)
calculation") introduced a check for the minimum resource size to span
at least 8 registers. However, the DS1WM only has 6 registers:

DS1WM_CMD       0x00    /* R/W 4 bits command */
DS1WM_DATA      0x01    /* R/W 8 bits, transmit/receive buffer */
DS1WM_INT       0x02    /* R/W interrupt status */
DS1WM_INT_EN    0x03    /* R/W interrupt enable */
DS1WM_CLKDIV    0x04    /* R/W 5 bits of divisor and pre-scale */
DS1WM_CNTRL     0x05    /* R/W master control register */

This causes the probe to fail incorrectly when the actual resource size of
6 is specified instead of 8.

Fixes: 242b476f821b ("w1: ds1wm: fix register offset (bus shift) calculation")
Signed-off-by: Julian Haller <julian.haller@...lips.com>
---
 drivers/w1/masters/ds1wm.c | 7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

diff --git a/drivers/w1/masters/ds1wm.c b/drivers/w1/masters/ds1wm.c
index f661695fb589..0ecb14772f30 100644
--- a/drivers/w1/masters/ds1wm.c
+++ b/drivers/w1/masters/ds1wm.c
@@ -544,13 +544,12 @@ static int ds1wm_probe(struct platform_device *pdev)
 		return -EINVAL;
 	}
 
-	ds1wm_data->bus_shift = plat->bus_shift;
-	/* make sure resource has space for 8 registers */
-	if ((8 << ds1wm_data->bus_shift) > resource_size(res)) {
+	/* make sure resource has space for 6 registers */
+	if ((6 << ds1wm_data->bus_shift) > resource_size(res)) {
 		dev_err(&ds1wm_data->pdev->dev,
 			"memory resource size %d to small, should be %d\n",
 			(int)resource_size(res),
-			8 << ds1wm_data->bus_shift);
+			6 << ds1wm_data->bus_shift);
 		return -EINVAL;
 	}
 
-- 
2.25.1