drivers: net: cpsw: fix for cpsw crash when build as modules

When CPSW and Davinci MDIO are build as modules, CPSW crashes when
accessing CPSW registers in CPSW probe. The same is working in built-in
as the CPSW clocks are enabled in Davindi MDIO probe, SO Enabling the
clocks before accessing the version register and moving out the other
register access to cpsw device open.

Signed-off-by: Mugunthan V N <mugunthanvnm@ti.com>
Signed-off-by: Felipe Balbi <balbi@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/ti/cpsw.c

@@ -1151,6 +1151,12 @@ static int cpsw_ndo_open(struct net_device *ndev)
 		 * receive descs
 		 */
 		cpsw_info(priv, ifup, "submitted %d rx descriptors\n", i);
+
+		if (cpts_register(&priv->pdev->dev, priv->cpts,
+				  priv->data.cpts_clock_mult,
+				  priv->data.cpts_clock_shift))
+			dev_err(priv->dev, "error registering cpts device\n");
+
 	}
 
 	/* Enable Interrupt pacing if configured */
@@ -1197,6 +1203,7 @@ static int cpsw_ndo_stop(struct net_device *ndev)
 	netif_carrier_off(priv->ndev);
 
 	if (cpsw_common_res_usage_state(priv) <= 1) {
+		cpts_unregister(priv->cpts);
 		cpsw_intr_disable(priv);
 		cpdma_ctlr_int_ctrl(priv->dma, false);
 		cpdma_ctlr_stop(priv->dma);
@@ -1985,9 +1992,15 @@ static int cpsw_probe(struct platform_device *pdev)
 		goto clean_runtime_disable_ret;
 	}
 	priv->regs = ss_regs;
-	priv->version = __raw_readl(&priv->regs->id_ver);
 	priv->host_port = HOST_PORT_NUM;
 
+	/* Need to enable clocks with runtime PM api to access module
+	 * registers
+	 */
+	pm_runtime_get_sync(&pdev->dev);
+	priv->version = readl(&priv->regs->id_ver);
+	pm_runtime_put_sync(&pdev->dev);
+
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
 	priv->wr_regs = devm_ioremap_resource(&pdev->dev, res);
 	if (IS_ERR(priv->wr_regs)) {
@@ -2157,8 +2170,6 @@ static int cpsw_remove(struct platform_device *pdev)
 		unregister_netdev(cpsw_get_slave_ndev(priv, 1));
 	unregister_netdev(ndev);
 
-	cpts_unregister(priv->cpts);
-
 	cpsw_ale_destroy(priv->ale);
 	cpdma_chan_destroy(priv->txch);
 	cpdma_chan_destroy(priv->rxch);