net: stmmac: socfpga: Remove re-registration of reset controller

Both socfpga_dwmac_parse_data() in dwmac-socfpga.c and stmmac_dvr_probe()
in stmmac_main.c functions call devm_reset_control_get() to register an
reset controller for the stmmac. This results in an attempt to register
two reset controllers for the same non-shared reset line.

The first attempt to register the reset controller works fine. The second
attempt fails with warning from the reset controller core, see below.
The warning is produced because the reset line is non-shared and thus
it is allowed to have only up-to one reset controller associated with
that reset line, not two or more.

The solution has multiple parts. First, the original socfpga_dwmac_init()
is tweaked to use reset controller pointer from the stmmac_priv (private
data of the stmmac core) instead of the local instance, which was used
before. The local re-registration of the reset controller is removed.

Next, the socfpga_dwmac_init() is moved after stmmac_dvr_probe() in the
probe function. This order is legal according to Altera and it makes the
code much easier, since there is no need to temporarily register and
unregister the reset controller ; the reset controller is already registered
by the stmmac_dvr_probe().

Finally, plat_dat->exit and socfpga_dwmac_exit() is no longer necessary,
since the functionality is already performed by the stmmac core.

------------[ cut here ]------------
WARNING: CPU: 0 PID: 1 at drivers/reset/core.c:187 __of_reset_control_get+0x218/0x270
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.6.0-rc4-next-20160419-00015-gabb2477-dirty #4
Hardware name: Altera SOCFPGA
[<c010f290>] (unwind_backtrace) from [<c010b82c>] (show_stack+0x10/0x14)
[<c010b82c>] (show_stack) from [<c0373da4>] (dump_stack+0x94/0xa8)
[<c0373da4>] (dump_stack) from [<c011bcc0>] (__warn+0xec/0x104)
[<c011bcc0>] (__warn) from [<c011bd88>] (warn_slowpath_null+0x20/0x28)
[<c011bd88>] (warn_slowpath_null) from [<c03a6eb4>] (__of_reset_control_get+0x218/0x270)
[<c03a6eb4>] (__of_reset_control_get) from [<c03a701c>] (__devm_reset_control_get+0x54/0x90)
[<c03a701c>] (__devm_reset_control_get) from [<c041fa30>] (stmmac_dvr_probe+0x1b4/0x8e8)
[<c041fa30>] (stmmac_dvr_probe) from [<c04298c8>] (socfpga_dwmac_probe+0x1b8/0x28c)
[<c04298c8>] (socfpga_dwmac_probe) from [<c03d6ffc>] (platform_drv_probe+0x4c/0xb0)
[<c03d6ffc>] (platform_drv_probe) from [<c03d54ec>] (driver_probe_device+0x224/0x2bc)
[<c03d54ec>] (driver_probe_device) from [<c03d5630>] (__driver_attach+0xac/0xb0)
[<c03d5630>] (__driver_attach) from [<c03d382c>] (bus_for_each_dev+0x6c/0xa0)
[<c03d382c>] (bus_for_each_dev) from [<c03d4ad4>] (bus_add_driver+0x1a4/0x21c)
[<c03d4ad4>] (bus_add_driver) from [<c03d60ac>] (driver_register+0x78/0xf8)
[<c03d60ac>] (driver_register) from [<c0101760>] (do_one_initcall+0x40/0x170)
[<c0101760>] (do_one_initcall) from [<c0800e38>] (kernel_init_freeable+0x1dc/0x27c)
[<c0800e38>] (kernel_init_freeable) from [<c05d1bd4>] (kernel_init+0x8/0x114)
[<c05d1bd4>] (kernel_init) from [<c01076f8>] (ret_from_fork+0x14/0x3c)
---[ end trace 059d2fbe87608fa9 ]---
Signed-off-by: Marek Vasut <marex@denx.de>
Cc: Matthew Gerlach <mgerlach@opensource.altera.com>
Cc: Dinh Nguyen <dinguyen@opensource.altera.com>
Cc: David S. Miller <davem@davemloft.net>
Tested-by: Dinh Nguyen <dinguyen@opensource.altera.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/stmicro/stmmac/dwmac-socfpga.c

@@ -49,7 +49,6 @@ struct socfpga_dwmac {
 	u32	reg_shift;
 	struct	device *dev;
 	struct regmap *sys_mgr_base_addr;
-	struct reset_control *stmmac_rst;
 	void __iomem *splitter_base;
 	bool f2h_ptp_ref_clk;
 };
@@ -92,15 +91,6 @@ static int socfpga_dwmac_parse_data(struct socfpga_dwmac *dwmac, struct device *
 	struct device_node *np_splitter;
 	struct resource res_splitter;
 
-	dwmac->stmmac_rst = devm_reset_control_get(dev,
-						  STMMAC_RESOURCE_NAME);
-	if (IS_ERR(dwmac->stmmac_rst)) {
-		dev_info(dev, "Could not get reset control!\n");
-		if (PTR_ERR(dwmac->stmmac_rst) == -EPROBE_DEFER)
-			return -EPROBE_DEFER;
-		dwmac->stmmac_rst = NULL;
-	}
-
 	dwmac->interface = of_get_phy_mode(np);
 
 	sys_mgr_base_addr = syscon_regmap_lookup_by_phandle(np, "altr,sysmgr-syscon");
@@ -194,30 +184,23 @@ static int socfpga_dwmac_setup(struct socfpga_dwmac *dwmac)
 	return 0;
 }
 
-static void socfpga_dwmac_exit(struct platform_device *pdev, void *priv)
-{
-	struct socfpga_dwmac	*dwmac = priv;
-
-	/* On socfpga platform exit, assert and hold reset to the
-	 * enet controller - the default state after a hard reset.
-	 */
-	if (dwmac->stmmac_rst)
-		reset_control_assert(dwmac->stmmac_rst);
-}
-
 static int socfpga_dwmac_init(struct platform_device *pdev, void *priv)
 {
-	struct socfpga_dwmac	*dwmac = priv;
+	struct socfpga_dwmac *dwmac = priv;
 	struct net_device *ndev = platform_get_drvdata(pdev);
 	struct stmmac_priv *stpriv = NULL;
 	int ret = 0;
 
-	if (ndev)
-		stpriv = netdev_priv(ndev);
+	if (!ndev)
+		return -EINVAL;
+
+	stpriv = netdev_priv(ndev);
+	if (!stpriv)
+		return -EINVAL;
 
 	/* Assert reset to the enet controller before changing the phy mode */
-	if (dwmac->stmmac_rst)
-		reset_control_assert(dwmac->stmmac_rst);
+	if (stpriv->stmmac_rst)
+		reset_control_assert(stpriv->stmmac_rst);
 
 	/* Setup the phy mode in the system manager registers according to
 	 * devicetree configuration
@@ -227,8 +210,8 @@ static int socfpga_dwmac_init(struct platform_device *pdev, void *priv)
 	/* Deassert reset for the phy configuration to be sampled by
 	 * the enet controller, and operation to start in requested mode
 	 */
-	if (dwmac->stmmac_rst)
-		reset_control_deassert(dwmac->stmmac_rst);
+	if (stpriv->stmmac_rst)
+		reset_control_deassert(stpriv->stmmac_rst);
 
 	/* Before the enet controller is suspended, the phy is suspended.
 	 * This causes the phy clock to be gated. The enet controller is
@@ -245,7 +228,7 @@ static int socfpga_dwmac_init(struct platform_device *pdev, void *priv)
 	 * control register 0, and can be modified by the phy driver
 	 * framework.
 	 */
-	if (stpriv && stpriv->phydev)
+	if (stpriv->phydev)
 		phy_resume(stpriv->phydev);
 
 	return ret;
@@ -285,14 +268,13 @@ static int socfpga_dwmac_probe(struct platform_device *pdev)
 
 	plat_dat->bsp_priv = dwmac;
 	plat_dat->init = socfpga_dwmac_init;
-	plat_dat->exit = socfpga_dwmac_exit;
 	plat_dat->fix_mac_speed = socfpga_dwmac_fix_mac_speed;
 
-	ret = socfpga_dwmac_init(pdev, plat_dat->bsp_priv);
-	if (ret)
-		return ret;
+	ret = stmmac_dvr_probe(&pdev->dev, plat_dat, &stmmac_res);
+	if (!ret)
+		ret = socfpga_dwmac_init(pdev, dwmac);
 
-	return stmmac_dvr_probe(&pdev->dev, plat_dat, &stmmac_res);
+	return ret;
 }
 
 static const struct of_device_id socfpga_dwmac_match[] = {