linux-kernel - [PATCH 2/2] ata: ahci: mvebu: override ahci_stop

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Date:   Wed, 25 Apr 2018 12:27:14 +0800
From:   <xswang@...vell.com>
To:     <linux-ide@...r.kernel.org>, <tj@...nel.org>,
        <linux-kernel@...r.kernel.org>
CC:     <oferh@...vell.com>, <dingwei@...vell.com>, <xigu@...vell.com>,
        <nadavh@...vell.com>, Evan Wang <xswang@...vell.com>,
        Thomas Petazzoni <thomas.petazzoni@...tlin.com>,
        <stable@...r.kernel.org>
Subject: [PATCH 2/2] ata: ahci: mvebu: override ahci_stop_engine for mvebu AHCI

From: Evan Wang <xswang@...vell.com>

There is an issue(Errata Ref#226) that the SATA can not be
detected via SATA Port-MultiPlayer(PMP) with following
error log:
  ata1.15: PMP product ID mismatch
  ata1.15: SATA link up 6.0 Gbps (SStatus 133 SControl 300)
  ata1.15: Port Multiplier vendor mismatch '0x1b4b'!='0x0'
  ata1.15: PMP revalidation failed (errno=-19)

After debugging, the reason is found that the value Port-x
FIS-based Switching Control(PxFBS@...0) become wrong.
According to design, the bits[11:8, 0] of register PxFBS
are cleared when Port Command and Status (0x18) bit[0]
changes its value from 1 to 0, i.e. falling edge of Port
Command and Status bit[0] sends PULSE that resets PxFBS
bits[11:8; 0].
So it needs a mvebu SATA WA to save the port PxFBS register
before PxCMD ST write and restore it afterwards.

This patch implements the WA in a separate function of
ahci_mvebu_stop_engine to override ahci_stop_gngine.

Signed-off-by: Evan Wang <xswang@...vell.com>
Suggested-by: Ofer Heifetz <oferh@...vell.com>
Cc: Tejun Heo <tj@...nel.org>
Cc: Thomas Petazzoni <thomas.petazzoni@...tlin.com>
Cc: stable@...r.kernel.org
---
 drivers/ata/ahci_mvebu.c | 56 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/drivers/ata/ahci_mvebu.c b/drivers/ata/ahci_mvebu.c
index de7128d..0045dac 100644
--- a/drivers/ata/ahci_mvebu.c
+++ b/drivers/ata/ahci_mvebu.c
@@ -62,6 +62,60 @@ static void ahci_mvebu_regret_option(struct ahci_host_priv *hpriv)
 	writel(0x80, hpriv->mmio + AHCI_VENDOR_SPECIFIC_0_DATA);
 }
 
+/**
+ * ahci_mvebu_stop_engine
+ *
+ * @ap:	Target ata port
+ *
+ * Errata Ref#226 - SATA Disk HOT swap issue when connected through
+ * Port Multiplier in FIS-based Switching mode.
+ *
+ * To avoid the issue, according to design, the bits[11:8, 0] of
+ * register PxFBS are cleared when Port Command and Status (0x18) bit[0]
+ * changes its value from 1 to 0, i.e. falling edge of Port
+ * Command and Status bit[0] sends PULSE that resets PxFBS
+ * bits[11:8; 0].
+ *
+ * This function is used to override function of "ahci_stop_engine"
+ * from libahci.c by adding the mvebu work around(WA) to save PxFBS
+ * value before the PxCMD ST write of 0, then restore PxFBS value.
+ *
+ * Return: 0 on success; Error code otherwise.
+ */
+int ahci_mvebu_stop_engine(struct ata_port *ap)
+{
+	void __iomem *port_mmio = ahci_port_base(ap);
+	u32 tmp, port_fbs;
+
+	tmp = readl(port_mmio + PORT_CMD);
+
+	/* check if the HBA is idle */
+	if ((tmp & (PORT_CMD_START | PORT_CMD_LIST_ON)) == 0)
+		return 0;
+
+	/* save the port PxFBS register for later restore */
+	port_fbs = readl(port_mmio + PORT_FBS);
+
+	/* setting HBA to idle */
+	tmp &= ~PORT_CMD_START;
+	writel(tmp, port_mmio + PORT_CMD);
+
+	/*
+	 * bit #15 PxCMD signal doesn't clear PxFBS,
+	 * restore the PxFBS register right after clearing the PxCMD ST,
+	 * no need to wait for the PxCMD bit #15.
+	 */
+	writel(port_fbs, port_mmio + PORT_FBS);
+
+	/* wait for engine to stop. This could be as long as 500 msec */
+	tmp = ata_wait_register(ap, port_mmio + PORT_CMD,
+				PORT_CMD_LIST_ON, PORT_CMD_LIST_ON, 1, 500);
+	if (tmp & PORT_CMD_LIST_ON)
+		return -EIO;
+
+	return 0;
+}
+
 #ifdef CONFIG_PM_SLEEP
 static int ahci_mvebu_suspend(struct platform_device *pdev, pm_message_t state)
 {
@@ -112,6 +166,8 @@ static int ahci_mvebu_probe(struct platform_device *pdev)
 	if (rc)
 		return rc;
 
+	hpriv->stop_engine = ahci_mvebu_stop_engine;
+
 	if (of_device_is_compatible(pdev->dev.of_node,
 				    "marvell,armada-380-ahci")) {
 		dram = mv_mbus_dram_info();
-- 
1.9.1