From e67f325e9cd67562b761e884680c0fec03a6f404 Mon Sep 17 00:00:00 2001
From: Matthew Hagan <mnhagan88@gmail.com>
Date: Tue, 8 Jun 2021 19:59:06 +0100
Subject: net: stmmac: explicitly deassert GMAC_AHB_RESET

We are currently assuming that GMAC_AHB_RESET will already be deasserted
by the bootloader. However if this has not been done, probing of the GMAC
will fail. To remedy this we must ensure GMAC_AHB_RESET has been deasserted
prior to probing.

v2 changes:
 - remove NULL condition check for stmmac_ahb_rst in stmmac_main.c
 - unwrap dev_err() message in stmmac_main.c
 - add PTR_ERR() around plat->stmmac_ahb_rst in stmmac_platform.c

v3 changes:
 - add error pointer to dev_err() output
 - add reset_control_assert(stmmac_ahb_rst) in stmmac_dvr_remove
 - revert PTR_ERR() around plat->stmmac_ahb_rst since this is performed
   on the returned value of ret by the calling function

Signed-off-by: Matthew Hagan <mnhagan88@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
 drivers/net/ethernet/stmicro/stmmac/stmmac_main.c     | 5 +++++
 drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c | 6 ++++++
 include/linux/stmmac.h                                | 1 +
 3 files changed, 12 insertions(+)

--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
@@ -5033,6 +5033,10 @@ int stmmac_dvr_probe(struct device *devi
 			reset_control_reset(priv->plat->stmmac_rst);
 	}
 
+	ret = reset_control_deassert(priv->plat->stmmac_ahb_rst);
+	if (ret == -ENOTSUPP)
+		dev_err(priv->device, "unable to bring out of ahb reset\n");
+
 	/* Init MAC and get the capabilities */
 	ret = stmmac_hw_init(priv);
 	if (ret)
@@ -5247,6 +5251,7 @@ int stmmac_dvr_remove(struct device *dev
 	phylink_destroy(priv->phylink);
 	if (priv->plat->stmmac_rst)
 		reset_control_assert(priv->plat->stmmac_rst);
+	reset_control_assert(priv->plat->stmmac_ahb_rst);
 	pm_runtime_put(dev);
 	pm_runtime_disable(dev);
 	if (priv->hw->pcs != STMMAC_PCS_TBI &&
--- a/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
+++ b/drivers/net/ethernet/stmicro/stmmac/stmmac_platform.c
@@ -616,6 +616,12 @@ stmmac_probe_config_dt(struct platform_d
 		plat->stmmac_rst = NULL;
 	}
 
+	plat->stmmac_ahb_rst = devm_reset_control_get_optional_shared(
+							&pdev->dev, "ahb");
+	if (IS_ERR(plat->stmmac_ahb_rst))
+		if (PTR_ERR(plat->stmmac_ahb_rst) == -EPROBE_DEFER)
+			goto error_hw_init;
+
 	return plat;
 
 error_hw_init:
--- a/include/linux/stmmac.h
+++ b/include/linux/stmmac.h
@@ -192,6 +192,7 @@ struct plat_stmmacenet_data {
 	unsigned int clk_ref_rate;
 	s32 ptp_max_adj;
 	struct reset_control *stmmac_rst;
+	struct reset_control *stmmac_ahb_rst;
 	struct stmmac_axi *axi;
 	int has_gmac4;
 	bool has_sun8i;
