[PATCH net-next v3 2/3] net: stmmac: Allow drivers to provide a default AXI configuration

[Thierry Reding <thierry.reding@gmail.com>]

From: Thierry Reding <treding@nvidia.com>

In many cases the AXI configuration can be derived from the compatible
string, so there's no need to add the configuration to DT. Allow drivers
to pass in the default AXI configuration so they can be properly set up
without extra data in DT.

Signed-off-by: Thierry Reding <treding@nvidia.com>
---
Changes in v3:
- add comments to help explain override logic
- add missing kerneldoc for new parameter

Changes in v2:
- fix bisectability
---
 drivers/net/ethernet/stmicro/stmmac/stmmac.h       |  2 +
 .../net/ethernet/stmicro/stmmac/stmmac_platform.c  | 59 +++++++++++++++-------
 2 files changed, 43 insertions(+), 18 deletions(-)

diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac.h b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
index dddcaa9220cc..573c5d99b4d6 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac.h
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac.h
@@ -36,6 +36,8 @@ struct stmmac_resources {
 	int sfty_ue_irq;
 	int rx_irq[MTL_MAX_RX_QUEUES];
 	int tx_irq[MTL_MAX_TX_QUEUES];
+
+	const struct stmmac_axi *axi;
 };
 
 enum stmmac_txbuf_type {
diff --git a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
index 4e2eb54306f9..583f78ae9bb0 100644
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -87,38 +87,61 @@ static int dwmac1000_validate_ucast_entries(struct device *dev,
 /**
  * stmmac_axi_setup - parse DT parameters for programming the AXI register
  * @pdev: platform device
+ * @res: driver-specific parameters
  * Description:
- * if required, from device-tree the AXI internal register can be tuned
- * by using platform parameters.
+ * Use driver-specific defaults for the AXI internal registers if available,
+ * or parse them from device tree, if present. Driver-specific defaults can
+ * be overridden by the values from device tree.
  */
-static struct stmmac_axi *stmmac_axi_setup(struct platform_device *pdev)
+static struct stmmac_axi *stmmac_axi_setup(struct platform_device *pdev,
+					   struct stmmac_resources *res)
 {
 	struct device_node *np;
 	struct stmmac_axi *axi;
 
+	/*
+	 * Exit early if the driver hasn't provided any defaults and the
+	 * device tree doesn't specify values for the AXI configuration.
+	 */
 	np = of_parse_phandle(pdev->dev.of_node, "snps,axi-config", 0);
-	if (!np)
+	if (!np && !res->axi)
 		return NULL;
 
 	axi = devm_kzalloc(&pdev->dev, sizeof(*axi), GFP_KERNEL);
 	if (!axi) {
-		of_node_put(np);
+		if (np)
+			of_node_put(np);
+
 		return ERR_PTR(-ENOMEM);
 	}
 
-	axi->axi_lpi_en = of_property_read_bool(np, "snps,lpi_en");
-	axi->axi_xit_frm = of_property_read_bool(np, "snps,xit_frm");
-	axi->axi_kbbe = of_property_read_bool(np, "snps,kbbe");
-	axi->axi_fb = of_property_read_bool(np, "snps,fb");
-	axi->axi_mb = of_property_read_bool(np, "snps,mb");
-	axi->axi_rb =  of_property_read_bool(np, "snps,rb");
+	/* copy defaults provided by the driver */
+	if (res->axi)
+		*axi = *res->axi;
+
+	/* override defaults with data from DT */
+	if (np) {
+		axi->axi_lpi_en = of_property_read_bool(np, "snps,lpi_en");
+		axi->axi_xit_frm = of_property_read_bool(np, "snps,xit_frm");
+		axi->axi_kbbe = of_property_read_bool(np, "snps,kbbe");
+		axi->axi_fb = of_property_read_bool(np, "snps,fb");
+		axi->axi_mb = of_property_read_bool(np, "snps,mb");
+		axi->axi_rb =  of_property_read_bool(np, "snps,rb");
+
+		if (of_property_read_u32(np, "snps,wr_osr_lmt", &axi->axi_wr_osr_lmt)) {
+			if (!res->axi)
+				axi->axi_wr_osr_lmt = 1;
+		}
 
-	if (of_property_read_u32(np, "snps,wr_osr_lmt", &axi->axi_wr_osr_lmt))
-		axi->axi_wr_osr_lmt = 1;
-	if (of_property_read_u32(np, "snps,rd_osr_lmt", &axi->axi_rd_osr_lmt))
-		axi->axi_rd_osr_lmt = 1;
-	of_property_read_u32_array(np, "snps,blen", axi->axi_blen, AXI_BLEN);
-	of_node_put(np);
+		if (of_property_read_u32(np, "snps,rd_osr_lmt", &axi->axi_rd_osr_lmt)) {
+			if (!res->axi)
+				axi->axi_rd_osr_lmt = 1;
+		}
+
+		of_property_read_u32_array(np, "snps,blen", axi->axi_blen, AXI_BLEN);
+
+		of_node_put(np);
+	}
 
 	return axi;
 }
@@ -606,7 +629,7 @@ stmmac_probe_config_dt(struct platform_device *pdev,
 
 	of_property_read_u32(np, "snps,ps-speed", &plat->mac_port_sel_speed);
 
-	plat->axi = stmmac_axi_setup(pdev);
+	plat->axi = stmmac_axi_setup(pdev, res);
 
 	rc = stmmac_mtl_setup(pdev, plat);
 	if (rc) {

-- 
2.43.2