linux-kernel - [PATCH v2 2/2] nvmem: core: Allow getting nvmem cell with a NULL cell id

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Message-Id: <1484030729-28577-2-git-send-email-vivek.gautam@codeaurora.org>
Date:   Tue, 10 Jan 2017 12:15:29 +0530
From:   Vivek Gautam <vivek.gautam@...eaurora.org>
To:     srinivas.kandagatla@...aro.org, linux-kernel@...r.kernel.org
Cc:     maxime.ripard@...e-electrons.com, sboyd@...eaurora.org,
        linux-arm-msm@...r.kernel.org,
        Vivek Gautam <vivek.gautam@...eaurora.org>
Subject: [PATCH v2 2/2] nvmem: core: Allow getting nvmem cell with a NULL cell id

The nvmem cell with a NULL cell name/id should be the one
with no accompanying 'nvmem-cell-names' property, and thus
will be the cell at index 0 in the device tree.
So, we default to index 0 and update the cell index only when
nvmem cell name id exists.

Suggested-by: Stephen Boyd <sboyd@...eaurora.org>
Signed-off-by: Vivek Gautam <vivek.gautam@...eaurora.org>
Reviewed-by: Stephen Boyd <sboyd@...eaurora.org>
---

Based on torvald's master branch.

This patch supersedes the earlier posted series [1] that added
support to get nvmem cell by index. We don't need that patch-series.

Changes since v1:
 - Fixed the typo s/acoompanying/accompanying.
 - Added 'Reviewed-by' from Stephen.

[1] https://lkml.org/lkml/2016/12/23/80

 drivers/nvmem/core.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/nvmem/core.c b/drivers/nvmem/core.c
index 5eb796acc79a..12e271f31cea 100644
--- a/drivers/nvmem/core.c
+++ b/drivers/nvmem/core.c
@@ -747,7 +747,9 @@ static struct nvmem_cell *nvmem_cell_get_from_list(const char *cell_id)
  * of_nvmem_cell_get() - Get a nvmem cell from given device node and cell id
  *
  * @np: Device tree node that uses the nvmem cell.
- * @name: nvmem cell name from nvmem-cell-names property.
+ * @name: nvmem cell name from nvmem-cell-names property, or NULL
+ *	  for the cell at index 0 (the lone cell with no accompanying
+ *	  nvmem-cell-names property).
  *
  * Return: Will be an ERR_PTR() on error or a valid pointer
  * to a struct nvmem_cell.  The nvmem_cell will be freed by the
@@ -760,9 +762,12 @@ struct nvmem_cell *of_nvmem_cell_get(struct device_node *np,
 	struct nvmem_cell *cell;
 	struct nvmem_device *nvmem;
 	const __be32 *addr;
-	int rval, len, index;
+	int rval, len;
+	int index = 0;
 
-	index = of_property_match_string(np, "nvmem-cell-names", name);
+	/* if cell name exists, find index to the name */
+	if (name)
+		index = of_property_match_string(np, "nvmem-cell-names", name);
 
 	cell_np = of_parse_phandle(np, "nvmem-cells", index);
 	if (!cell_np)
-- 
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