linux-kernel - [PATCH V2 2/2] ata: ahci: ceva: Update the driver to support xilinx GT phy

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Date:   Tue, 22 Sep 2020 15:45:13 +0530
From:   Piyush Mehta <piyush.mehta@...inx.com>
To:     axboe@...nel.dk, p.zabel@...gutronix.de, robh+dt@...nel.org
Cc:     linux-ide@...r.kernel.org, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, git@...inx.com, sgoud@...inx.com,
        michal.simek@...inx.com, Piyush Mehta <piyush.mehta@...inx.com>
Subject: [PATCH V2 2/2] ata: ahci: ceva: Update the driver to support xilinx GT phy

SATA controller used in Xilinx ZynqMP platform uses xilinx GT phy
which has 4 GT lanes and can used by 4 peripherals at a time.
SATA controller uses 1 GT phy lane among the 4 GT lanes. To configure
the GT lane for SATA controller, the below sequence is expected.

1. Assert the SATA controller reset.
2. Configure the xilinx GT phy lane for SATA controller (phy_init).
3. De-assert the SATA controller reset.
4. Wait for PLL of the GT lane used by SATA to be locked (phy_power_on).

The ahci_platform_enable_resources() by default does the phy_init()
and phy_power_on() but the default sequence doesn't work with Xilinx
platforms. Because of this reason, updated the driver to support the
new sequence.

Added is_rst_ctrl flag, for backward compatibility with the older
sequence. If the reset controller is not available, then the SATA
controller will configure with the older sequences.

Signed-off-by: Piyush Mehta <piyush.mehta@...inx.com>
---
 drivers/ata/ahci_ceva.c | 39 +++++++++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/drivers/ata/ahci_ceva.c b/drivers/ata/ahci_ceva.c
index b10fd4c..c704906 100644
--- a/drivers/ata/ahci_ceva.c
+++ b/drivers/ata/ahci_ceva.c
@@ -12,6 +12,7 @@
 #include <linux/module.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 #include "ahci.h"
 
 /* Vendor Specific Register Offsets */
@@ -87,6 +88,7 @@ struct ceva_ahci_priv {
 	u32 axicc;
 	bool is_cci_enabled;
 	int flags;
+	struct reset_control *rst;
 };
 
 static unsigned int ceva_ahci_read_id(struct ata_device *dev,
@@ -194,7 +196,7 @@ static int ceva_ahci_probe(struct platform_device *pdev)
 	struct ahci_host_priv *hpriv;
 	struct ceva_ahci_priv *cevapriv;
 	enum dev_dma_attr attr;
-	int rc;
+	int rc, i, is_rst_ctrl = 1;
 
 	cevapriv = devm_kzalloc(dev, sizeof(*cevapriv), GFP_KERNEL);
 	if (!cevapriv)
@@ -202,14 +204,47 @@ static int ceva_ahci_probe(struct platform_device *pdev)
 
 	cevapriv->ahci_pdev = pdev;
 
+	cevapriv->rst = devm_reset_control_get(&pdev->dev, NULL);
+	if (IS_ERR(cevapriv->rst)) {
+		if (PTR_ERR(cevapriv->rst) != -EPROBE_DEFER)
+			dev_err(&pdev->dev, "failed to get reset: %ld\n",
+				PTR_ERR(cevapriv->rst));
+		is_rst_ctrl = 0;
+	}
+
 	hpriv = ahci_platform_get_resources(pdev, 0);
 	if (IS_ERR(hpriv))
 		return PTR_ERR(hpriv);
+	if (is_rst_ctrl)
+		rc = ahci_platform_enable_clks(hpriv);
+	else
+		rc = ahci_platform_enable_resources(hpriv);
 
-	rc = ahci_platform_enable_resources(hpriv);
 	if (rc)
 		return rc;
 
+	if (is_rst_ctrl) {
+		/* Assert the controller reset */
+		reset_control_assert(cevapriv->rst);
+
+		for (i = 0; i < hpriv->nports; i++) {
+			rc = phy_init(hpriv->phys[i]);
+			if (rc)
+				return rc;
+		}
+
+		/* De-assert the controller reset */
+		reset_control_deassert(cevapriv->rst);
+
+		for (i = 0; i < hpriv->nports; i++) {
+			rc = phy_power_on(hpriv->phys[i]);
+			if (rc) {
+				phy_exit(hpriv->phys[i]);
+				return rc;
+			}
+		}
+	}
+
 	if (of_property_read_bool(np, "ceva,broken-gen2"))
 		cevapriv->flags = CEVA_FLAG_BROKEN_GEN2;
 
-- 
2.7.4