linux/drivers/pci/host/pci-imx6.c
Tim Harvey 3fce0e882f PCI: imx6: Delay enabling reference clock for SS until it stabilizes
According to the IMX6 reference manuals, REF_SSP_EN (Reference clock enable
for SS function) must remain deasserted until the reference clock is
running at the appropriate frequency.

Delay enabling the reference clock for the SS function until it has
stabilized.  This prevents a high link failure rate (>5%) on certain IMX6
boards at various temperatures.

[bhelgaas: reword changelog slightly]
Tested-by: Fabio Estevam <festevam@gmail.com>
Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Marek Vasut <marex@denx.de>
Acked-by: Lucas Stach <l.stach@pengutronix.de>
2014-09-05 11:16:41 -06:00

656 lines
17 KiB
C

/*
* PCIe host controller driver for Freescale i.MX6 SoCs
*
* Copyright (C) 2013 Kosagi
* http://www.kosagi.com
*
* Author: Sean Cross <xobs@kosagi.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*/
#include <linux/clk.h>
#include <linux/delay.h>
#include <linux/gpio.h>
#include <linux/kernel.h>
#include <linux/mfd/syscon.h>
#include <linux/mfd/syscon/imx6q-iomuxc-gpr.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/pci.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/resource.h>
#include <linux/signal.h>
#include <linux/types.h>
#include <linux/interrupt.h>
#include "pcie-designware.h"
#define to_imx6_pcie(x) container_of(x, struct imx6_pcie, pp)
struct imx6_pcie {
int reset_gpio;
struct clk *pcie_bus;
struct clk *pcie_phy;
struct clk *pcie;
struct pcie_port pp;
struct regmap *iomuxc_gpr;
void __iomem *mem_base;
};
/* PCIe Root Complex registers (memory-mapped) */
#define PCIE_RC_LCR 0x7c
#define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1 0x1
#define PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2 0x2
#define PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK 0xf
/* PCIe Port Logic registers (memory-mapped) */
#define PL_OFFSET 0x700
#define PCIE_PL_PFLR (PL_OFFSET + 0x08)
#define PCIE_PL_PFLR_LINK_STATE_MASK (0x3f << 16)
#define PCIE_PL_PFLR_FORCE_LINK (1 << 15)
#define PCIE_PHY_DEBUG_R0 (PL_OFFSET + 0x28)
#define PCIE_PHY_DEBUG_R1 (PL_OFFSET + 0x2c)
#define PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING (1 << 29)
#define PCIE_PHY_DEBUG_R1_XMLH_LINK_UP (1 << 4)
#define PCIE_PHY_CTRL (PL_OFFSET + 0x114)
#define PCIE_PHY_CTRL_DATA_LOC 0
#define PCIE_PHY_CTRL_CAP_ADR_LOC 16
#define PCIE_PHY_CTRL_CAP_DAT_LOC 17
#define PCIE_PHY_CTRL_WR_LOC 18
#define PCIE_PHY_CTRL_RD_LOC 19
#define PCIE_PHY_STAT (PL_OFFSET + 0x110)
#define PCIE_PHY_STAT_ACK_LOC 16
#define PCIE_LINK_WIDTH_SPEED_CONTROL 0x80C
#define PORT_LOGIC_SPEED_CHANGE (0x1 << 17)
/* PHY registers (not memory-mapped) */
#define PCIE_PHY_RX_ASIC_OUT 0x100D
#define PHY_RX_OVRD_IN_LO 0x1005
#define PHY_RX_OVRD_IN_LO_RX_DATA_EN (1 << 5)
#define PHY_RX_OVRD_IN_LO_RX_PLL_EN (1 << 3)
static int pcie_phy_poll_ack(void __iomem *dbi_base, int exp_val)
{
u32 val;
u32 max_iterations = 10;
u32 wait_counter = 0;
do {
val = readl(dbi_base + PCIE_PHY_STAT);
val = (val >> PCIE_PHY_STAT_ACK_LOC) & 0x1;
wait_counter++;
if (val == exp_val)
return 0;
udelay(1);
} while (wait_counter < max_iterations);
return -ETIMEDOUT;
}
static int pcie_phy_wait_ack(void __iomem *dbi_base, int addr)
{
u32 val;
int ret;
val = addr << PCIE_PHY_CTRL_DATA_LOC;
writel(val, dbi_base + PCIE_PHY_CTRL);
val |= (0x1 << PCIE_PHY_CTRL_CAP_ADR_LOC);
writel(val, dbi_base + PCIE_PHY_CTRL);
ret = pcie_phy_poll_ack(dbi_base, 1);
if (ret)
return ret;
val = addr << PCIE_PHY_CTRL_DATA_LOC;
writel(val, dbi_base + PCIE_PHY_CTRL);
ret = pcie_phy_poll_ack(dbi_base, 0);
if (ret)
return ret;
return 0;
}
/* Read from the 16-bit PCIe PHY control registers (not memory-mapped) */
static int pcie_phy_read(void __iomem *dbi_base, int addr , int *data)
{
u32 val, phy_ctl;
int ret;
ret = pcie_phy_wait_ack(dbi_base, addr);
if (ret)
return ret;
/* assert Read signal */
phy_ctl = 0x1 << PCIE_PHY_CTRL_RD_LOC;
writel(phy_ctl, dbi_base + PCIE_PHY_CTRL);
ret = pcie_phy_poll_ack(dbi_base, 1);
if (ret)
return ret;
val = readl(dbi_base + PCIE_PHY_STAT);
*data = val & 0xffff;
/* deassert Read signal */
writel(0x00, dbi_base + PCIE_PHY_CTRL);
ret = pcie_phy_poll_ack(dbi_base, 0);
if (ret)
return ret;
return 0;
}
static int pcie_phy_write(void __iomem *dbi_base, int addr, int data)
{
u32 var;
int ret;
/* write addr */
/* cap addr */
ret = pcie_phy_wait_ack(dbi_base, addr);
if (ret)
return ret;
var = data << PCIE_PHY_CTRL_DATA_LOC;
writel(var, dbi_base + PCIE_PHY_CTRL);
/* capture data */
var |= (0x1 << PCIE_PHY_CTRL_CAP_DAT_LOC);
writel(var, dbi_base + PCIE_PHY_CTRL);
ret = pcie_phy_poll_ack(dbi_base, 1);
if (ret)
return ret;
/* deassert cap data */
var = data << PCIE_PHY_CTRL_DATA_LOC;
writel(var, dbi_base + PCIE_PHY_CTRL);
/* wait for ack de-assertion */
ret = pcie_phy_poll_ack(dbi_base, 0);
if (ret)
return ret;
/* assert wr signal */
var = 0x1 << PCIE_PHY_CTRL_WR_LOC;
writel(var, dbi_base + PCIE_PHY_CTRL);
/* wait for ack */
ret = pcie_phy_poll_ack(dbi_base, 1);
if (ret)
return ret;
/* deassert wr signal */
var = data << PCIE_PHY_CTRL_DATA_LOC;
writel(var, dbi_base + PCIE_PHY_CTRL);
/* wait for ack de-assertion */
ret = pcie_phy_poll_ack(dbi_base, 0);
if (ret)
return ret;
writel(0x0, dbi_base + PCIE_PHY_CTRL);
return 0;
}
/* Added for PCI abort handling */
static int imx6q_pcie_abort_handler(unsigned long addr,
unsigned int fsr, struct pt_regs *regs)
{
return 0;
}
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);
}
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;
}
static int imx6_pcie_deassert_core_reset(struct pcie_port *pp)
{
struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
int ret;
ret = clk_prepare_enable(imx6_pcie->pcie_phy);
if (ret) {
dev_err(pp->dev, "unable to enable pcie_phy clock\n");
goto err_pcie_phy;
}
ret = clk_prepare_enable(imx6_pcie->pcie_bus);
if (ret) {
dev_err(pp->dev, "unable to enable pcie_bus clock\n");
goto err_pcie_bus;
}
ret = clk_prepare_enable(imx6_pcie->pcie);
if (ret) {
dev_err(pp->dev, "unable to enable pcie clock\n");
goto err_pcie;
}
/* allow the clocks to stabilize */
usleep_range(200, 500);
/* power up core phy and enable ref clock */
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
IMX6Q_GPR1_PCIE_TEST_PD, 0 << 18);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR1,
IMX6Q_GPR1_PCIE_REF_CLK_EN, 1 << 16);
/* Some boards don't have PCIe reset GPIO. */
if (gpio_is_valid(imx6_pcie->reset_gpio)) {
gpio_set_value(imx6_pcie->reset_gpio, 0);
msleep(100);
gpio_set_value(imx6_pcie->reset_gpio, 1);
}
return 0;
err_pcie:
clk_disable_unprepare(imx6_pcie->pcie_bus);
err_pcie_bus:
clk_disable_unprepare(imx6_pcie->pcie_phy);
err_pcie_phy:
return ret;
}
static void imx6_pcie_init_phy(struct pcie_port *pp)
{
struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
IMX6Q_GPR12_PCIE_CTL_2, 0 << 10);
/* configure constant input signal to the pcie ctrl and phy */
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
IMX6Q_GPR12_DEVICE_TYPE, PCI_EXP_TYPE_ROOT_PORT << 12);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
IMX6Q_GPR12_LOS_LEVEL, 9 << 4);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
IMX6Q_GPR8_TX_DEEMPH_GEN1, 0 << 0);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
IMX6Q_GPR8_TX_DEEMPH_GEN2_3P5DB, 0 << 6);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
IMX6Q_GPR8_TX_DEEMPH_GEN2_6DB, 20 << 12);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
IMX6Q_GPR8_TX_SWING_FULL, 127 << 18);
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR8,
IMX6Q_GPR8_TX_SWING_LOW, 127 << 25);
}
static int imx6_pcie_wait_for_link(struct pcie_port *pp)
{
int count = 200;
while (!dw_pcie_link_up(pp)) {
usleep_range(100, 1000);
if (--count)
continue;
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 0;
}
static irqreturn_t imx6_pcie_msi_handler(int irq, void *arg)
{
struct pcie_port *pp = arg;
return dw_handle_msi_irq(pp);
}
static int imx6_pcie_start_link(struct pcie_port *pp)
{
struct imx6_pcie *imx6_pcie = to_imx6_pcie(pp);
uint32_t tmp;
int ret, count;
/*
* Force Gen1 operation when starting the link. In case the link is
* started in Gen2 mode, there is a possibility the devices on the
* bus will not be detected at all. This happens with PCIe switches.
*/
tmp = readl(pp->dbi_base + PCIE_RC_LCR);
tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
tmp |= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN1;
writel(tmp, pp->dbi_base + PCIE_RC_LCR);
/* Start LTSSM. */
regmap_update_bits(imx6_pcie->iomuxc_gpr, IOMUXC_GPR12,
IMX6Q_GPR12_PCIE_CTL_2, 1 << 10);
ret = imx6_pcie_wait_for_link(pp);
if (ret)
return ret;
/* Allow Gen2 mode after the link is up. */
tmp = readl(pp->dbi_base + PCIE_RC_LCR);
tmp &= ~PCIE_RC_LCR_MAX_LINK_SPEEDS_MASK;
tmp |= PCIE_RC_LCR_MAX_LINK_SPEEDS_GEN2;
writel(tmp, pp->dbi_base + PCIE_RC_LCR);
/*
* Start Directed Speed Change so the best possible speed both link
* partners support can be negotiated.
*/
tmp = readl(pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);
tmp |= PORT_LOGIC_SPEED_CHANGE;
writel(tmp, pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);
count = 200;
while (count--) {
tmp = readl(pp->dbi_base + PCIE_LINK_WIDTH_SPEED_CONTROL);
/* Test if the speed change finished. */
if (!(tmp & PORT_LOGIC_SPEED_CHANGE))
break;
usleep_range(100, 1000);
}
/* Make sure link training is finished as well! */
if (count)
ret = imx6_pcie_wait_for_link(pp);
else
ret = -EINVAL;
if (ret) {
dev_err(pp->dev, "Failed to bring link up!\n");
} else {
tmp = readl(pp->dbi_base + 0x80);
dev_dbg(pp->dev, "Link up, Gen=%i\n", (tmp >> 16) & 0xf);
}
return ret;
}
static void imx6_pcie_host_init(struct pcie_port *pp)
{
imx6_pcie_assert_core_reset(pp);
imx6_pcie_init_phy(pp);
imx6_pcie_deassert_core_reset(pp);
dw_pcie_setup_rc(pp);
imx6_pcie_start_link(pp);
if (IS_ENABLED(CONFIG_PCI_MSI))
dw_pcie_msi_init(pp);
}
static void imx6_pcie_reset_phy(struct pcie_port *pp)
{
uint32_t temp;
pcie_phy_read(pp->dbi_base, PHY_RX_OVRD_IN_LO, &temp);
temp |= (PHY_RX_OVRD_IN_LO_RX_DATA_EN |
PHY_RX_OVRD_IN_LO_RX_PLL_EN);
pcie_phy_write(pp->dbi_base, PHY_RX_OVRD_IN_LO, temp);
usleep_range(2000, 3000);
pcie_phy_read(pp->dbi_base, PHY_RX_OVRD_IN_LO, &temp);
temp &= ~(PHY_RX_OVRD_IN_LO_RX_DATA_EN |
PHY_RX_OVRD_IN_LO_RX_PLL_EN);
pcie_phy_write(pp->dbi_base, PHY_RX_OVRD_IN_LO, temp);
}
static int imx6_pcie_link_up(struct pcie_port *pp)
{
u32 rc, debug_r0, rx_valid;
int count = 5;
/*
* Test if the PHY reports that the link is up and also that the LTSSM
* training finished. There are three possible states of the link when
* this code is called:
* 1) The link is DOWN (unlikely)
* The link didn't come up yet for some reason. This usually means
* we have a real problem somewhere. Reset the PHY and exit. This
* state calls for inspection of the DEBUG registers.
* 2) The link is UP, but still in LTSSM training
* Wait for the training to finish, which should take a very short
* time. If the training does not finish, we have a problem and we
* need to inspect the DEBUG registers. If the training does finish,
* the link is up and operating correctly.
* 3) The link is UP and no longer in LTSSM training
* The link is up and operating correctly.
*/
while (1) {
rc = readl(pp->dbi_base + PCIE_PHY_DEBUG_R1);
if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_UP))
break;
if (!(rc & PCIE_PHY_DEBUG_R1_XMLH_LINK_IN_TRAINING))
return 1;
if (!count--)
break;
dev_dbg(pp->dev, "Link is up, but still in training\n");
/*
* Wait a little bit, then re-check if the link finished
* the training.
*/
usleep_range(1000, 2000);
}
/*
* From L0, initiate MAC entry to gen2 if EP/RC supports gen2.
* Wait 2ms (LTSSM timeout is 24ms, PHY lock is ~5us in gen2).
* If (MAC/LTSSM.state == Recovery.RcvrLock)
* && (PHY/rx_valid==0) then pulse PHY/rx_reset. Transition
* to gen2 is stuck
*/
pcie_phy_read(pp->dbi_base, PCIE_PHY_RX_ASIC_OUT, &rx_valid);
debug_r0 = readl(pp->dbi_base + PCIE_PHY_DEBUG_R0);
if (rx_valid & 0x01)
return 0;
if ((debug_r0 & 0x3f) != 0x0d)
return 0;
dev_err(pp->dev, "transition to gen2 is stuck, reset PHY!\n");
dev_dbg(pp->dev, "debug_r0=%08x debug_r1=%08x\n", debug_r0, rc);
imx6_pcie_reset_phy(pp);
return 0;
}
static struct pcie_host_ops imx6_pcie_host_ops = {
.link_up = imx6_pcie_link_up,
.host_init = imx6_pcie_host_init,
};
static int __init imx6_add_pcie_port(struct pcie_port *pp,
struct platform_device *pdev)
{
int ret;
if (IS_ENABLED(CONFIG_PCI_MSI)) {
pp->msi_irq = platform_get_irq_byname(pdev, "msi");
if (pp->msi_irq <= 0) {
dev_err(&pdev->dev, "failed to get MSI irq\n");
return -ENODEV;
}
ret = devm_request_irq(&pdev->dev, pp->msi_irq,
imx6_pcie_msi_handler,
IRQF_SHARED, "mx6-pcie-msi", pp);
if (ret) {
dev_err(&pdev->dev, "failed to request MSI irq\n");
return -ENODEV;
}
}
pp->root_bus_nr = -1;
pp->ops = &imx6_pcie_host_ops;
ret = dw_pcie_host_init(pp);
if (ret) {
dev_err(&pdev->dev, "failed to initialize host\n");
return ret;
}
return 0;
}
static int __init imx6_pcie_probe(struct platform_device *pdev)
{
struct imx6_pcie *imx6_pcie;
struct pcie_port *pp;
struct device_node *np = pdev->dev.of_node;
struct resource *dbi_base;
int ret;
imx6_pcie = devm_kzalloc(&pdev->dev, sizeof(*imx6_pcie), GFP_KERNEL);
if (!imx6_pcie)
return -ENOMEM;
pp = &imx6_pcie->pp;
pp->dev = &pdev->dev;
/* Added for PCI abort handling */
hook_fault_code(16 + 6, imx6q_pcie_abort_handler, SIGBUS, 0,
"imprecise external abort");
dbi_base = platform_get_resource(pdev, IORESOURCE_MEM, 0);
pp->dbi_base = devm_ioremap_resource(&pdev->dev, dbi_base);
if (IS_ERR(pp->dbi_base))
return PTR_ERR(pp->dbi_base);
/* Fetch GPIOs */
imx6_pcie->reset_gpio = of_get_named_gpio(np, "reset-gpio", 0);
if (gpio_is_valid(imx6_pcie->reset_gpio)) {
ret = devm_gpio_request_one(&pdev->dev, imx6_pcie->reset_gpio,
GPIOF_OUT_INIT_LOW, "PCIe reset");
if (ret) {
dev_err(&pdev->dev, "unable to get reset gpio\n");
return ret;
}
}
/* Fetch clocks */
imx6_pcie->pcie_phy = devm_clk_get(&pdev->dev, "pcie_phy");
if (IS_ERR(imx6_pcie->pcie_phy)) {
dev_err(&pdev->dev,
"pcie_phy clock source missing or invalid\n");
return PTR_ERR(imx6_pcie->pcie_phy);
}
imx6_pcie->pcie_bus = devm_clk_get(&pdev->dev, "pcie_bus");
if (IS_ERR(imx6_pcie->pcie_bus)) {
dev_err(&pdev->dev,
"pcie_bus clock source missing or invalid\n");
return PTR_ERR(imx6_pcie->pcie_bus);
}
imx6_pcie->pcie = devm_clk_get(&pdev->dev, "pcie");
if (IS_ERR(imx6_pcie->pcie)) {
dev_err(&pdev->dev,
"pcie clock source missing or invalid\n");
return PTR_ERR(imx6_pcie->pcie);
}
/* Grab GPR config register range */
imx6_pcie->iomuxc_gpr =
syscon_regmap_lookup_by_compatible("fsl,imx6q-iomuxc-gpr");
if (IS_ERR(imx6_pcie->iomuxc_gpr)) {
dev_err(&pdev->dev, "unable to find iomuxc registers\n");
return PTR_ERR(imx6_pcie->iomuxc_gpr);
}
ret = imx6_add_pcie_port(pp, pdev);
if (ret < 0)
return ret;
platform_set_drvdata(pdev, imx6_pcie);
return 0;
}
static void imx6_pcie_shutdown(struct platform_device *pdev)
{
struct imx6_pcie *imx6_pcie = platform_get_drvdata(pdev);
/* bring down link, so bootloader gets clean state in case of reboot */
imx6_pcie_assert_core_reset(&imx6_pcie->pp);
}
static const struct of_device_id imx6_pcie_of_match[] = {
{ .compatible = "fsl,imx6q-pcie", },
{},
};
MODULE_DEVICE_TABLE(of, imx6_pcie_of_match);
static struct platform_driver imx6_pcie_driver = {
.driver = {
.name = "imx6q-pcie",
.owner = THIS_MODULE,
.of_match_table = imx6_pcie_of_match,
},
.shutdown = imx6_pcie_shutdown,
};
/* Freescale PCIe driver does not allow module unload */
static int __init imx6_pcie_init(void)
{
return platform_driver_probe(&imx6_pcie_driver, imx6_pcie_probe);
}
module_init(imx6_pcie_init);
MODULE_AUTHOR("Sean Cross <xobs@kosagi.com>");
MODULE_DESCRIPTION("Freescale i.MX6 PCIe host controller driver");
MODULE_LICENSE("GPL v2");