ahci: imx: setup power saving methods

In order to save power consumption as much as possible.

* Disable sata phy internal pll reference clock when sysetem enter
  into suspend mode, enable it after resume.

* Setup module parameter used to enable imx ahci test power down
  mode(PDDQ) or not, when there is no device detected on the port

* minor modifications:
  - The format of the copyright is changed, because that the original
    one can't pass fsl internal patch reivew without the character
    '(c)'.
  - Exports ahci_platform_ops and ahci_error_handler().

NOTE:
* The hot-plug can't be supported when PDDQ mode is ever enabled.

* module parameter usage how-to:
  - default: enable PDDQ mode when no device detected.
  - add "ahci-imx.hotplug=1" into kernel command line if your don't
    want to enable PDDQ mode when no device detected on the port.

tj: Slightly updated description and comments.

Signed-off-by: Richard Zhu <r65037@freescale.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

drivers/ata/ahci.h

@@ -339,6 +339,7 @@ extern struct device_attribute *ahci_sdev_attrs[];
 	.sdev_attrs		= ahci_sdev_attrs
 
 extern struct ata_port_operations ahci_ops;
+extern struct ata_port_operations ahci_platform_ops;
 extern struct ata_port_operations ahci_pmp_retry_srst_ops;
 
 unsigned int ahci_dev_classify(struct ata_port *ap);
@@ -368,6 +369,7 @@ irqreturn_t ahci_hw_interrupt(int irq, void *dev_instance);
 irqreturn_t ahci_thread_fn(int irq, void *dev_instance);
 void ahci_print_info(struct ata_host *host, const char *scc_s);
 int ahci_host_activate(struct ata_host *host, int irq, unsigned int n_msis);
+void ahci_error_handler(struct ata_port *ap);
 
 static inline void __iomem *__ahci_port_base(struct ata_host *host,
 					     unsigned int port_no)

drivers/ata/ahci_imx.c

@@ -1,6 +1,6 @@
 /*
+ * copyright (c) 2013 Freescale Semiconductor, Inc.
  * Freescale IMX AHCI SATA platform driver
- * Copyright 2013 Freescale Semiconductor, Inc.
  *
  * based on the AHCI SATA platform driver by Jeff Garzik and Anton Vorontsov
  *
@@ -25,10 +25,13 @@
 #include <linux/of_device.h>
 #include <linux/mfd/syscon.h>
 #include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
+#include <linux/libata.h>
 #include "ahci.h"
 
 enum {
-	HOST_TIMER1MS = 0xe0, /* Timer 1-ms */
+	PORT_PHY_CTL = 0x178,			/* Port0 PHY Control */
+	PORT_PHY_CTL_PDDQ_LOC = 0x100000,	/* PORT_PHY_CTL bits */
+	HOST_TIMER1MS = 0xe0,			/* Timer 1-ms */
 };
 
 struct imx_ahci_priv {
@@ -36,6 +39,56 @@ struct imx_ahci_priv {
 	struct clk *sata_ref_clk;
 	struct clk *ahb_clk;
 	struct regmap *gpr;
+	bool no_device;
+	bool first_time;
+};
+
+static int ahci_imx_hotplug;
+module_param_named(hotplug, ahci_imx_hotplug, int, 0644);
+MODULE_PARM_DESC(hotplug, "AHCI IMX hot-plug support (0=Don't support, 1=support)");
+
+static void ahci_imx_error_handler(struct ata_port *ap)
+{
+	u32 reg_val;
+	struct ata_device *dev;
+	struct ata_host *host = dev_get_drvdata(ap->dev);
+	struct ahci_host_priv *hpriv = host->private_data;
+	void __iomem *mmio = hpriv->mmio;
+	struct imx_ahci_priv *imxpriv = dev_get_drvdata(ap->dev->parent);
+
+	ahci_error_handler(ap);
+
+	if (!(imxpriv->first_time) || ahci_imx_hotplug)
+		return;
+
+	imxpriv->first_time = false;
+
+	ata_for_each_dev(dev, &ap->link, ENABLED)
+		return;
+	/*
+	 * Disable link to save power.  An imx ahci port can't be recovered
+	 * without full reset once the pddq mode is enabled making it
+	 * impossible to use as part of libata LPM.
+	 */
+	reg_val = readl(mmio + PORT_PHY_CTL);
+	writel(reg_val | PORT_PHY_CTL_PDDQ_LOC, mmio + PORT_PHY_CTL);
+	regmap_update_bits(imxpriv->gpr, IOMUXC_GPR13,
+			IMX6Q_GPR13_SATA_MPLL_CLK_EN,
+			!IMX6Q_GPR13_SATA_MPLL_CLK_EN);
+	clk_disable_unprepare(imxpriv->sata_ref_clk);
+	imxpriv->no_device = true;
+}
+
+static struct ata_port_operations ahci_imx_ops = {
+	.inherits	= &ahci_platform_ops,
+	.error_handler	= ahci_imx_error_handler,
+};
+
+static const struct ata_port_info ahci_imx_port_info = {
+	.flags		= AHCI_FLAG_COMMON,
+	.pio_mask	= ATA_PIO4,
+	.udma_mask	= ATA_UDMA6,
+	.port_ops	= &ahci_imx_ops,
 };
 
 static int imx6q_sata_init(struct device *dev, void __iomem *mmio)
@@ -117,9 +170,51 @@ static void imx6q_sata_exit(struct device *dev)
 	clk_disable_unprepare(imxpriv->sata_ref_clk);
 }
 
+static int imx_ahci_suspend(struct device *dev)
+{
+	struct imx_ahci_priv *imxpriv =  dev_get_drvdata(dev->parent);
+
+	/*
+	 * If no_device is set, The CLKs had been gated off in the
+	 * initialization so don't do it again here.
+	 */
+	if (!imxpriv->no_device) {
+		regmap_update_bits(imxpriv->gpr, IOMUXC_GPR13,
+				IMX6Q_GPR13_SATA_MPLL_CLK_EN,
+				!IMX6Q_GPR13_SATA_MPLL_CLK_EN);
+		clk_disable_unprepare(imxpriv->sata_ref_clk);
+	}
+
+	return 0;
+}
+
+static int imx_ahci_resume(struct device *dev)
+{
+	struct imx_ahci_priv *imxpriv =  dev_get_drvdata(dev->parent);
+	int ret;
+
+	if (!imxpriv->no_device) {
+		ret = clk_prepare_enable(imxpriv->sata_ref_clk);
+		if (ret < 0) {
+			dev_err(dev, "pre-enable sata_ref clock err:%d\n", ret);
+			return ret;
+		}
+
+		regmap_update_bits(imxpriv->gpr, IOMUXC_GPR13,
+				IMX6Q_GPR13_SATA_MPLL_CLK_EN,
+				IMX6Q_GPR13_SATA_MPLL_CLK_EN);
+		usleep_range(1000, 2000);
+	}
+
+	return 0;
+}
+
 static struct ahci_platform_data imx6q_sata_pdata = {
 	.init = imx6q_sata_init,
 	.exit = imx6q_sata_exit,
+	.ata_port_info = &ahci_imx_port_info,
+	.suspend = imx_ahci_suspend,
+	.resume = imx_ahci_resume,
 };
 
 static const struct of_device_id imx_ahci_of_match[] = {
@@ -152,6 +247,8 @@ static int imx_ahci_probe(struct platform_device *pdev)
 	ahci_dev = &ahci_pdev->dev;
 	ahci_dev->parent = dev;
 
+	imxpriv->no_device = false;
+	imxpriv->first_time = true;
 	imxpriv->ahb_clk = devm_clk_get(dev, "ahb");
 	if (IS_ERR(imxpriv->ahb_clk)) {
 		dev_err(dev, "can't get ahb clock.\n");

drivers/ata/ahci_platform.c

@@ -49,10 +49,11 @@ static struct platform_device_id ahci_devtype[] = {
 };
 MODULE_DEVICE_TABLE(platform, ahci_devtype);
 
-static struct ata_port_operations ahci_platform_ops = {
+struct ata_port_operations ahci_platform_ops = {
 	.inherits	= &ahci_ops,
 	.host_stop	= ahci_host_stop,
 };
+EXPORT_SYMBOL_GPL(ahci_platform_ops);
 
 static struct ata_port_operations ahci_platform_retry_srst_ops = {
 	.inherits	= &ahci_pmp_retry_srst_ops,

drivers/ata/libahci.c

@@ -89,7 +89,6 @@ static int ahci_pmp_retry_softreset(struct ata_link *link, unsigned int *class,
 static int ahci_hardreset(struct ata_link *link, unsigned int *class,
 			  unsigned long deadline);
 static void ahci_postreset(struct ata_link *link, unsigned int *class);
-static void ahci_error_handler(struct ata_port *ap);
 static void ahci_post_internal_cmd(struct ata_queued_cmd *qc);
 static void ahci_dev_config(struct ata_device *dev);
 #ifdef CONFIG_PM
@@ -1982,7 +1981,7 @@ static void ahci_thaw(struct ata_port *ap)
 	writel(pp->intr_mask, port_mmio + PORT_IRQ_MASK);
 }
 
-static void ahci_error_handler(struct ata_port *ap)
+void ahci_error_handler(struct ata_port *ap)
 {
 	if (!(ap->pflags & ATA_PFLAG_FROZEN)) {
 		/* restart engine */
@@ -1995,6 +1994,7 @@ static void ahci_error_handler(struct ata_port *ap)
 	if (!ata_dev_enabled(ap->link.device))
 		ahci_stop_engine(ap);
 }
+EXPORT_SYMBOL_GPL(ahci_error_handler);
 
 static void ahci_post_internal_cmd(struct ata_queued_cmd *qc)
 {