PCI: designware: Add generic dw_pcie_wait_for_link()

Several DesignWare-based drivers (dra7xx, exynos, imx6, keystone, qcom, and
spear13xx) had similar loops waiting for the link to come up.

Add a generic dw_pcie_wait_for_link() for use by all these drivers so the
waiting is done consistently, e.g., always using usleep_range() rather than
mdelay() and using similar timeouts and retry counts.

Note that this changes the Keystone link training/wait for link strategy,
so we initiate link training, then wait longer for the link to come up
before re-initiating link training.

[bhelgaas: changelog, split into its own patch, update pci-keystone.c, pcie-qcom.c]
Signed-off-by: Joao Pinto <[e-mail]>
Signed-off-by: Bjorn Helgaas <[e-mail]>
Acked-by: Pratyush Anand <[e-mail]>

drivers/pci/host/pci-dra7xx.c

···
  * published by the Free Software Foundation.
  */
 
-#include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/interrupt.h>
 #include <linux/irq.h>
···
 {
 	struct dra7xx_pcie *dra7xx = to_dra7xx_pcie(pp);
 	u32 reg;
-	unsigned int retries;
 
 	if (dw_pcie_link_up(pp)) {
 		dev_err(pp->dev, "link is already up\n");
···
 	reg |= LTSSM_EN;
 	dra7xx_pcie_writel(dra7xx, PCIECTRL_DRA7XX_CONF_DEVICE_CMD, reg);
 
-	for (retries = 0; retries < 1000; retries++) {
-		if (dw_pcie_link_up(pp))
-			return 0;
-		usleep_range(10, 20);
-	}
-
-	dev_err(pp->dev, "link is not up\n");
-	return -EINVAL;
+	return dw_pcie_wait_for_link(pp);
 }
 
 static void dra7xx_pcie_enable_interrupts(struct pcie_port *pp)

drivers/pci/host/pci-exynos.c

···
 {
 	struct exynos_pcie *exynos_pcie = to_exynos_pcie(pp);
 	u32 val;
-	unsigned int retries;
 
 	if (dw_pcie_link_up(pp)) {
 		dev_err(pp->dev, "Link already up\n");
···
 			  PCIE_APP_LTSSM_ENABLE);
 
 	/* check if the link is up or not */
-	for (retries = 0; retries < 10; retries++) {
-		if (dw_pcie_link_up(pp)) {
-			dev_info(pp->dev, "Link up\n");
-			return 0;
-		}
-		mdelay(100);
-	}
+	if (!dw_pcie_wait_for_link(pp))
+		return 0;
 
 	while (exynos_phy_readl(exynos_pcie, PCIE_PHY_PLL_LOCKED) == 0) {
 		val = exynos_blk_readl(exynos_pcie, PCIE_PHY_PLL_LOCKED);
···
 	/* power off phy */
 	exynos_pcie_power_off_phy(pp);
 
-	dev_err(pp->dev, "PCIe Link Fail\n");
-	return -EINVAL;
+	return -ETIMEDOUT;
 }
 
 static void exynos_pcie_clear_irq_pulse(struct pcie_port *pp)

drivers/pci/host/pci-imx6.c

···
 
 static int imx6_pcie_wait_for_link(struct pcie_port *pp)
 {
-	unsigned int retries;
+	/* check if the link is up or not */
+	if (!dw_pcie_wait_for_link(pp))
+		return 0;
 
-	for (retries = 0; retries < 200; retries++) {
-		if (dw_pcie_link_up(pp))
-			return 0;
-		usleep_range(100, 1000);
-	}
-
-	dev_err(pp->dev, "phy link never came up\n");
 	dev_dbg(pp->dev, "DEBUG_R0: 0x%08x, DEBUG_R1: 0x%08x\n",
 		readl(pp->dbi_base + PCIE_PHY_DEBUG_R0),
 		readl(pp->dbi_base + PCIE_PHY_DEBUG_R1));
-	return -EINVAL;
+	return -ETIMEDOUT;
 }
 
 static int imx6_pcie_wait_for_speed_change(struct pcie_port *pp)

drivers/pci/host/pci-keystone.c

···
 		return 0;
 	}
 
-	ks_dw_pcie_initiate_link_train(ks_pcie);
 	/* check if the link is up or not */
-	for (retries = 0; retries < 200; retries++) {
-		if (dw_pcie_link_up(pp))
-			return 0;
-		usleep_range(100, 1000);
+	for (retries = 0; retries < 5; retries++) {
 		ks_dw_pcie_initiate_link_train(ks_pcie);
+		if (!dw_pcie_wait_for_link(pp))
+			return 0;
 	}
 
 	dev_err(pp->dev, "phy link never came up\n");
-	return -EINVAL;
+	return -ETIMEDOUT;
 }
 
 static void ks_pcie_msi_irq_handler(struct irq_desc *desc)

drivers/pci/host/pcie-designware.c

···
 #include <linux/pci_regs.h>
 #include <linux/platform_device.h>
 #include <linux/types.h>
+#include <linux/delay.h>
 
 #include "pcie-designware.h"
 
···
 	.setup_irqs = dw_msi_setup_irqs,
 	.teardown_irq = dw_msi_teardown_irq,
 };
+
+int dw_pcie_wait_for_link(struct pcie_port *pp)
+{
+	int retries;
+
+	/* check if the link is up or not */
+	for (retries = 0; retries < LINK_WAIT_MAX_RETRIES; retries++) {
+		if (dw_pcie_link_up(pp)) {
+			dev_info(pp->dev, "link up\n");
+			return 0;
+		}
+		usleep_range(LINK_WAIT_USLEEP_MIN, LINK_WAIT_USLEEP_MAX);
+	}
+
+	dev_err(pp->dev, "phy link never came up\n");
+
+	return -ETIMEDOUT;
+}
 
 int dw_pcie_link_up(struct pcie_port *pp)
 {

drivers/pci/host/pcie-designware.h

···
 #define MAX_MSI_IRQS			32
 #define MAX_MSI_CTRLS			(MAX_MSI_IRQS / 32)
 
+/* Parameters for the waiting for link up routine */
+#define LINK_WAIT_MAX_RETRIES		10
+#define LINK_WAIT_USLEEP_MIN		90000
+#define LINK_WAIT_USLEEP_MAX		100000
+
 struct pcie_port {
 	struct device		*dev;
 	u8			root_bus_nr;
···
 int dw_pcie_cfg_write(void __iomem *addr, int size, u32 val);
 irqreturn_t dw_handle_msi_irq(struct pcie_port *pp);
 void dw_pcie_msi_init(struct pcie_port *pp);
+int dw_pcie_wait_for_link(struct pcie_port *pp);
 int dw_pcie_link_up(struct pcie_port *pp);
 void dw_pcie_setup_rc(struct pcie_port *pp);
 int dw_pcie_host_init(struct pcie_port *pp);

drivers/pci/host/pcie-qcom.c

···
 
 static int qcom_pcie_establish_link(struct qcom_pcie *pcie)
 {
-	struct device *dev = pcie->dev;
-	unsigned int retries = 0;
 	u32 val;
 
 	if (dw_pcie_link_up(&pcie->pp))
···
 	val |= PCIE20_ELBI_SYS_CTRL_LT_ENABLE;
 	writel(val, pcie->elbi + PCIE20_ELBI_SYS_CTRL);
 
-	do {
-		if (dw_pcie_link_up(&pcie->pp))
-			return 0;
-		usleep_range(250, 1000);
-	} while (retries < 200);
-
-	dev_warn(dev, "phy link never came up\n");
-
-	return -ETIMEDOUT;
+	return dw_pcie_wait_for_link(&pcie->pp);
 }
 
 static int qcom_pcie_get_resources_v0(struct qcom_pcie *pcie)

drivers/pci/host/pcie-spear13xx.c

···
  */
 
 #include <linux/clk.h>
-#include <linux/delay.h>
 #include <linux/interrupt.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
···
 	struct spear13xx_pcie *spear13xx_pcie = to_spear13xx_pcie(pp);
 	struct pcie_app_reg *app_reg = spear13xx_pcie->app_base;
 	u32 exp_cap_off = EXP_CAP_ID_OFFSET;
-	unsigned int retries;
 
 	if (dw_pcie_link_up(pp)) {
 		dev_err(pp->dev, "link already up\n");
···
 			| ((u32)1 << REG_TRANSLATION_ENABLE),
 			&app_reg->app_ctrl_0);
 
-	/* check if the link is up or not */
-	for (retries = 0; retries < 10; retries++) {
-		if (dw_pcie_link_up(pp)) {
-			dev_info(pp->dev, "link up\n");
-			return 0;
-		}
-		mdelay(100);
-	}
-
-	dev_err(pp->dev, "link Fail\n");
-	return -EINVAL;
+	return dw_pcie_wait_for_link(pp);
 }
 
 static irqreturn_t spear13xx_pcie_irq_handler(int irq, void *arg)