[PATCH 3/6] ata: ahci_brcm: Initialize the NSP interface clock and reset

[Florian Fainelli <florian.fainelli@broadcom.com>]

The NSP probe path assumes firmware has enabled the SATA IDM interface
clock and released the core reset. The downstream iProc config_AHCI()
sequence explicitly performs both operations before accessing AHCI.
Without that setup, a cold boot can access an inactive controller.

Map the optional NSP IDM register region and enable the interface clock
before releasing reset, retaining the downstream settling intervals.
Perform the sequence at probe and resume before reconfiguring SATA.

Keep the resource optional so older device trees continue to rely on
firmware initialization.

Fixes: 3ee2e6dcaa35 ("ata: ahci_brcm: Add support for Broadcom NSP SoC")
Signed-off-by: Florian Fainelli <florian.fainelli@broadcom.com>
---
 drivers/ata/ahci_brcm.c | 34 ++++++++++++++++++++++++++++++++++
 1 file changed, 34 insertions(+)

diff --git a/drivers/ata/ahci_brcm.c b/drivers/ata/ahci_brcm.c
index 29be74fedcf0..2ed60806b671 100644
--- a/drivers/ata/ahci_brcm.c
+++ b/drivers/ata/ahci_brcm.c
@@ -6,7 +6,9 @@
  */
 
 #include <linux/ahci_platform.h>
+#include <linux/bcma/bcma_regs.h>
 #include <linux/compiler.h>
+#include <linux/delay.h>
 #include <linux/device.h>
 #include <linux/init.h>
 #include <linux/interrupt.h>
@@ -83,6 +85,7 @@ enum brcm_ahci_quirks {
 struct brcm_ahci_priv {
 	struct device *dev;
 	void __iomem *top_ctrl;
+	void __iomem *idm;
 	u32 port_mask;
 	u32 quirks;
 	enum brcm_ahci_version version;
@@ -230,6 +233,25 @@ static u32 brcm_ahci_get_portmask(struct ahci_host_priv *hpriv,
 	return impl;
 }
 
+static void brcm_sata_init_idm(struct brcm_ahci_priv *priv)
+{
+	u32 data;
+
+	if (!priv->idm)
+		return;
+
+	/* Enable the interface clock before taking the SATA core out of reset. */
+	data = readl(priv->idm + BCMA_IOCTL);
+	writel(data | BCMA_IOCTL_CLK, priv->idm + BCMA_IOCTL);
+	readl(priv->idm + BCMA_IOCTL);
+	usleep_range(1000, 2000);
+
+	data = readl(priv->idm + BCMA_RESET_CTL);
+	writel(data & ~BCMA_RESET_CTL_RESET, priv->idm + BCMA_RESET_CTL);
+	readl(priv->idm + BCMA_RESET_CTL);
+	usleep_range(1000, 2000);
+}
+
 static void brcm_sata_init(struct brcm_ahci_priv *priv)
 {
 	void __iomem *ctrl = priv->top_ctrl + SATA_TOP_CTRL_BUS_CTRL;
@@ -369,6 +391,8 @@ static int __maybe_unused brcm_ahci_resume(struct device *dev)
 	struct brcm_ahci_priv *priv = hpriv->plat_data;
 	int ret = 0;
 
+	brcm_sata_init_idm(priv);
+
 	ret = reset_control_deassert(priv->rcdev_ahci);
 	if (ret)
 		return ret;
@@ -453,6 +477,14 @@ static int brcm_ahci_probe(struct platform_device *pdev)
 	priv->version = (unsigned long)of_id->data;
 	priv->dev = dev;
 
+	/* Older NSP device trees rely on firmware to initialize the IDM. */
+	if (priv->version == BRCM_SATA_NSP &&
+	    platform_get_resource_byname(pdev, IORESOURCE_MEM, "idm")) {
+		priv->idm = devm_platform_ioremap_resource_byname(pdev, "idm");
+		if (IS_ERR(priv->idm))
+			return PTR_ERR(priv->idm);
+	}
+
 	priv->top_ctrl = devm_platform_ioremap_resource_byname(pdev, "top-ctrl");
 	if (IS_ERR(priv->top_ctrl))
 		return PTR_ERR(priv->top_ctrl);
@@ -493,6 +525,8 @@ static int brcm_ahci_probe(struct platform_device *pdev)
 	if (ret)
 		return ret;
 
+	brcm_sata_init_idm(priv);
+
 	ret = ahci_platform_enable_clks(hpriv);
 	if (ret)
 		goto out_reset;
-- 
2.53.0