soc: qcom: cmd-db: Stop memcpy()ing in cmd_db_read_aux_data()

Let's change the function signature to return the pointer to memory or
an error pointer on failure, and take an argument that lets us return
the size of the aux data read. This way we can remove the
cmd_db_read_aux_data_len() API entirely and also get rid of the memcpy
operation from cmd_db to the caller. Updating the only user of this code
shows that making this change allows us to remove a function and put the
lookup where the user is.

Cc: Mahesh Sivasubramanian <[e-mail]>
Cc: Lina Iyer <[e-mail]>
Cc: Bjorn Andersson <[e-mail]>
Cc: Evan Green <[e-mail]>
Cc: Jordan Crouse <[e-mail]>
Cc: Rob Clark <[e-mail]>
Signed-off-by: Stephen Boyd <[e-mail]>
Signed-off-by: Andy Gross <[e-mail]>

drivers/gpu/drm/msm/adreno/a6xx_gmu.c

···
 	return ret;
 }
 
-/* Get the list of RPMh voltage levels from cmd-db */
-static int a6xx_gmu_rpmh_arc_cmds(const char *id, void *vals, int size)
-{
-	u32 len = cmd_db_read_aux_data_len(id);
-
-	if (!len)
-		return 0;
-
-	if (WARN_ON(len > size))
-		return -EINVAL;
-
-	cmd_db_read_aux_data(id, vals, len);
-
-	/*
-	 * The data comes back as an array of unsigned shorts so adjust the
-	 * count accordingly
-	 */
-	return len >> 1;
-}
-
 /* Return the 'arc-level' for the given frequency */
 static u32 a6xx_gmu_get_arc_level(struct device *dev, unsigned long freq)
 {
···
 }
 
 static int a6xx_gmu_rpmh_arc_votes_init(struct device *dev, u32 *votes,
-		unsigned long *freqs, int freqs_count,
-		u16 *pri, int pri_count,
-		u16 *sec, int sec_count)
+		unsigned long *freqs, int freqs_count, const char *id)
 {
 	int i, j;
+	const u16 *pri, *sec;
+	size_t pri_count, sec_count;
+
+	pri = cmd_db_read_aux_data(id, &pri_count);
+	/*
+	 * The data comes back as an array of unsigned shorts so adjust the
+	 * count accordingly
+	 */
+	pri_count >>= 1;
+	if (!pri_count)
+		return -EINVAL;
+
+	sec = cmd_db_read_aux_data("mx.lvl", &sec_count);
+	sec_count >>= 1;
+	if (!sec_count)
+		return -EINVAL;
 
 	/* Construct a vote for each frequency */
 	for (i = 0; i < freqs_count; i++) {
···
 	struct a6xx_gpu *a6xx_gpu = container_of(gmu, struct a6xx_gpu, gmu);
 	struct adreno_gpu *adreno_gpu = &a6xx_gpu->base;
 	struct msm_gpu *gpu = &adreno_gpu->base;
-
-	u16 gx[16], cx[16], mx[16];
-	u32 gxcount, cxcount, mxcount;
 	int ret;
-
-	/* Get the list of available voltage levels for each component */
-	gxcount = a6xx_gmu_rpmh_arc_cmds("gfx.lvl", gx, sizeof(gx));
-	cxcount = a6xx_gmu_rpmh_arc_cmds("cx.lvl", cx, sizeof(cx));
-	mxcount = a6xx_gmu_rpmh_arc_cmds("mx.lvl", mx, sizeof(mx));
 
 	/* Build the GX votes */
 	ret = a6xx_gmu_rpmh_arc_votes_init(&gpu->pdev->dev, gmu->gx_arc_votes,
-		gmu->gpu_freqs, gmu->nr_gpu_freqs,
-		gx, gxcount, mx, mxcount);
+		gmu->gpu_freqs, gmu->nr_gpu_freqs, "gfx.lvl");
 
 	/* Build the CX votes */
 	ret |= a6xx_gmu_rpmh_arc_votes_init(gmu->dev, gmu->cx_arc_votes,
-		gmu->gmu_freqs, gmu->nr_gmu_freqs,
-		cx, cxcount, mx, mxcount);
+		gmu->gmu_freqs, gmu->nr_gmu_freqs, "cx.lvl");
 
 	return ret;
 }

drivers/soc/qcom/cmd-db.c

···
 /**
  * cmd_db_read_aux_data() - Query command db for aux data.
  *
- *  @id: Resource to retrieve AUX Data on.
- *  @data: Data buffer to copy returned aux data to. Returns size on NULL
- *  @len: Caller provides size of data buffer passed in.
+ *  @id: Resource to retrieve AUX Data on
+ *  @len: size of data buffer returned
  *
- *  Return: size of data on success, errno otherwise
+ *  Return: pointer to data on success, error pointer otherwise
  */
-int cmd_db_read_aux_data(const char *id, u8 *data, size_t len)
+const void *cmd_db_read_aux_data(const char *id, size_t *len)
 {
 	int ret;
 	const struct entry_header *ent;
 	const struct rsc_hdr *rsc_hdr;
-	u16 ent_len;
-
-	if (!data)
-		return -EINVAL;
 
 	ret = cmd_db_get_header(id, &ent, &rsc_hdr);
 	if (ret)
-		return ret;
+		return ERR_PTR(ret);
 
-	ent_len = le16_to_cpu(ent->len);
-	if (len < ent_len)
-		return -EINVAL;
+	if (len)
+		*len = le16_to_cpu(ent->len);
 
-	len = min_t(u16, ent_len, len);
-	memcpy(data, rsc_offset(rsc_hdr, ent), len);
-
-	return len;
+	return rsc_offset(rsc_hdr, ent);
 }
 EXPORT_SYMBOL(cmd_db_read_aux_data);
-
-/**
- * cmd_db_read_aux_data_len - Get the length of the auxiliary data stored in DB.
- *
- * @id: Resource to retrieve AUX Data.
- *
- * Return: size on success, 0 on error
- */
-size_t cmd_db_read_aux_data_len(const char *id)
-{
-	int ret;
-	const struct entry_header *ent;
-
-	ret = cmd_db_get_header(id, &ent, NULL);
-
-	return ret < 0 ? 0 : le16_to_cpu(ent->len);
-}
-EXPORT_SYMBOL(cmd_db_read_aux_data_len);
 
 /**
  * cmd_db_read_slave_id - Get the slave ID for a given resource address

include/soc/qcom/cmd-db.h

···
 #if IS_ENABLED(CONFIG_QCOM_COMMAND_DB)
 u32 cmd_db_read_addr(const char *resource_id);
 
-int cmd_db_read_aux_data(const char *resource_id, u8 *data, size_t len);
-
-size_t cmd_db_read_aux_data_len(const char *resource_id);
+const void *cmd_db_read_aux_data(const char *resource_id, size_t *len);
 
 enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id);
 
···
 static inline u32 cmd_db_read_addr(const char *resource_id)
 { return 0; }
 
-static inline int cmd_db_read_aux_data(const char *resource_id, u8 *data,
-				       size_t len)
-{ return -ENODEV; }
-
-static inline size_t cmd_db_read_aux_data_len(const char *resource_id)
-{ return -ENODEV; }
+static inline const void *cmd_db_read_aux_data(const char *resource_id, size_t *len)
+{ return ERR_PTR(-ENODEV); }
 
 static inline enum cmd_db_hw_type cmd_db_read_slave_id(const char *resource_id)
 { return -ENODEV; }