[PATCH] PCI: imx6: Implement reset sequence for i.MX6+
From: Andrey Smirnov
Date: Wed Apr 13 2016 - 11:51:58 EST
I.MX6+ has a dedicated bit for reseting PCIe core, which should be used
instead of a regular reset sequence since using the latter will hang the
SoC.
This commit is based on c34068d48273e24d392d9a49a38be807954420ed from
http://git.freescale.com/git/cgit.cgi/imx/linux-2.6-imx.git
Signed-off-by: Andrey Smirnov <asmirnov@xxxxxxxxxxxxxxxxxxxxxxxxx>
---
arch/arm/boot/dts/imx6qp.dtsi | 3 ++
drivers/pci/host/pci-imx6.c | 82 +++++++++++++++++++----------
include/linux/mfd/syscon/imx6q-iomuxc-gpr.h | 1 +
3 files changed, 58 insertions(+), 28 deletions(-)
diff --git a/arch/arm/boot/dts/imx6qp.dtsi b/arch/arm/boot/dts/imx6qp.dtsi
index 1ada714..886dbf2 100644
--- a/arch/arm/boot/dts/imx6qp.dtsi
+++ b/arch/arm/boot/dts/imx6qp.dtsi
@@ -82,5 +82,8 @@
"ldb_di0", "ldb_di1", "prg";
};
+ pcie: pcie@0x01000000 {
+ compatible = "fsl,imx6qp-pcie", "snps,dw-pcie";
+ };
};
};
diff --git a/drivers/pci/host/pci-imx6.c b/drivers/pci/host/pci-imx6.c
index eb5a275..99f5cac 100644
--- a/drivers/pci/host/pci-imx6.c
+++ b/drivers/pci/host/pci-imx6.c
@@ -85,6 +85,14 @@ struct imx6_pcie {
#define PHY_RX_OVRD_IN_LO_RX_DATA_EN (1 << 5)
#define PHY_RX_OVRD_IN_LO_RX_PLL_EN (1 << 3)
+static inline bool is_imx6qp_pcie(struct imx6_pcie *imx6_pcie)
+{
+ struct pcie_port *pp = &imx6_pcie->pp;
+ struct device_node *np = pp->dev->of_node;
+
+ return of_device_is_compatible(np, "fsl,imx6qp-pcie");
+}
+
static int pcie_phy_poll_ack(void __iomem *dbi_base, int exp_val)
{
u32 val;
@@ -236,35 +244,44 @@ static int imx6_pcie_assert_core_reset(struct pcie_port *pp)
struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
u32 val, gpr1, gpr12;
- /*
- * If the bootloader already enabled the link we need some special
- * handling to get the core back into a state where it is safe to
- * touch it for configuration. As there is no dedicated reset signal
- * wired up for MX6QDL, we need to manually force LTSSM into "detect"
- * state before completely disabling LTSSM, which is a prerequisite
- * for core configuration.
- *
- * If both LTSSM_ENABLE and REF_SSP_ENABLE are active we have a strong
- * indication that the bootloader activated the link.
- */
- regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, &gpr1);
- regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, &gpr12);
-
- if ((gpr1 & IMX6Q_GPR1_PCIE_REF_CLK_EN) &&
- (gpr12 & IMX6Q_GPR12_PCIE_CTL_2)) {
- val = readl(pp->dbi_base + PCIE_PL_PFLR);
- val &= ~PCIE_PL_PFLR_LINK_STATE_MASK;
- val |= PCIE_PL_PFLR_FORCE_LINK;
- writel(val, pp->dbi_base + PCIE_PL_PFLR);
-
- regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
- IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);
- }
+ if (is_imx6qp_pcie(imx6_pcie)) {
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
+ IMX6Q_GPR1_PCIE_SW_RST,
+ IMX6Q_GPR1_PCIE_SW_RST);
+ } else {
+ /*
+ * If the bootloader already enabled the link we need
+ * some special handling to get the core back into a
+ * state where it is safe to touch it for
+ * configuration. As there is no dedicated reset
+ * signal wired up for MX6QDL, we need to manually
+ * force LTSSM into "detect" state before completely
+ * disabling LTSSM, which is a prerequisite for core
+ * configuration.
+ *
+ * If both LTSSM_ENABLE and REF_SSP_ENABLE are active
+ * we have a strong indication that the bootloader
+ * activated the link.
+ */
+ regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1, &gpr1);
+ regmap_read(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12, &gpr12);
+
+ if ((gpr1 & IMX6Q_GPR1_PCIE_REF_CLK_EN) &&
+ (gpr12 & IMX6Q_GPR12_PCIE_CTL_2)) {
+ val = readl(pp->dbi_base + PCIE_PL_PFLR);
+ val &= ~PCIE_PL_PFLR_LINK_STATE_MASK;
+ val |= PCIE_PL_PFLR_FORCE_LINK;
+ writel(val, pp->dbi_base + PCIE_PL_PFLR);
+
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
+ IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);
+ }
- regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
- IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18);
- regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
- IMX6Q_GPR1_PCIE_REF_CLK_EN, 0 << 16);
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
+ IMX6Q_GPR1_PCIE_TEST_PD, 1 << 18);
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
+ IMX6Q_GPR1_PCIE_REF_CLK_EN, 0 << 16);
+ }
return 0;
}
@@ -314,6 +331,14 @@ static int imx6_pcie_deassert_core_reset(struct pcie_port *pp)
msleep(100);
gpiod_set_value_cansleep(imx6_pcie->reset_gpio, 1);
}
+
+ if (is_imx6qp_pcie(imx6_pcie)) {
+ regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
+ IMX6Q_GPR1_PCIE_SW_RST, 0);
+
+ usleep_range(200, 500);
+ }
+
return 0;
err_pcie:
@@ -616,6 +641,7 @@ static void imx6_pcie_shutdown(struct platform_device *pdev)
static const struct of_device_id imx6_pcie_of_match[] = {
{ .compatible = "fsl,imx6q-pcie", },
+ { .compatible = "fsl,imx6qp-pcie", },
{},
};
MODULE_DEVICE_TABLE(of, imx6_pcie_of_match);
diff --git a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
index 238c8db..5b08e3c 100644
--- a/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
+++ b/include/linux/mfd/syscon/imx6q-iomuxc-gpr.h
@@ -95,6 +95,7 @@
#define IMX6Q_GPR0_DMAREQ_MUX_SEL0_IOMUX BIT(0)
#define IMX6Q_GPR1_PCIE_REQ_MASK (0x3 << 30)
+#define IMX6Q_GPR1_PCIE_SW_RST BIT(29)
#define IMX6Q_GPR1_PCIE_EXIT_L1 BIT(28)
#define IMX6Q_GPR1_PCIE_RDY_L23 BIT(27)
#define IMX6Q_GPR1_PCIE_ENTER_L1 BIT(26)
--
2.5.5