[PATCH 6/7] pci: Add DW PCIe controller support for iMX8MP SoC
Sumit Garg
sumit.garg at linaro.org
Wed Feb 21 07:25:16 CET 2024
On Tue, 20 Feb 2024 at 21:02, Marek Vasut <marex at denx.de> wrote:
>
> On 2/20/24 14:10, Sumit Garg wrote:
> > pcie_imx doesn't seem to share any useful code for iMX8 SoC and it is
> > tied to quite old port of pcie_designware driver from Linux which
> > suffices only iMX6 specific needs.
> >
> > But currently we have the common DWC specific bits which alligns pretty
> > well with DW PCIe controller on iMX8MP SoC. So lets reuse those common
> > bits instead as a new driver for iMX8 SoCs. It should be fairly easy to
> > add support for other iMX8 variants to this driver.
> >
> > iMX8MP SoC also comes up with standalone PCIe PHY support, so hence we
> > can reuse the generic PHY infrastructure to power on PCIe PHY.
> >
> > Signed-off-by: Sumit Garg <sumit.garg at linaro.org>
> > ---
> > drivers/pci/Kconfig | 8 +
> > drivers/pci/Makefile | 1 +
> > drivers/pci/pcie_dw_imx8.c | 348 +++++++++++++++++++++++++++++++++++++
> > 3 files changed, 357 insertions(+)
> > create mode 100644 drivers/pci/pcie_dw_imx8.c
> >
> > diff --git a/drivers/pci/Kconfig b/drivers/pci/Kconfig
> > index 463ec47eb92..b7c7922b091 100644
> > --- a/drivers/pci/Kconfig
> > +++ b/drivers/pci/Kconfig
> > @@ -413,4 +413,12 @@ config PCIE_STARFIVE_JH7110
> > Say Y here if you want to enable PLDA XpressRich PCIe controller
> > support on StarFive JH7110 SoC.
> >
> > +config PCIE_DW_IMX8
> > + bool "i.MX8 PCIe support"
> > + depends on ARCH_IMX8M
> > + select PCIE_DW_COMMON
> > + help
> > + Say Y here if you want to enable DW PCIe controller support on
> > + iMX8 SoCs.
> > +
> > endif
> > diff --git a/drivers/pci/Makefile b/drivers/pci/Makefile
> > index 72ef8b4bc77..cddbb902095 100644
> > --- a/drivers/pci/Makefile
> > +++ b/drivers/pci/Makefile
> > @@ -53,3 +53,4 @@ obj-$(CONFIG_PCIE_UNIPHIER) += pcie_uniphier.o
> > obj-$(CONFIG_PCIE_XILINX_NWL) += pcie-xilinx-nwl.o
> > obj-$(CONFIG_PCIE_PLDA_COMMON) += pcie_plda_common.o
> > obj-$(CONFIG_PCIE_STARFIVE_JH7110) += pcie_starfive_jh7110.o
> > +obj-$(CONFIG_PCIE_DW_IMX8) += pcie_dw_imx8.o
> > diff --git a/drivers/pci/pcie_dw_imx8.c b/drivers/pci/pcie_dw_imx8.c
> > new file mode 100644
> > index 00000000000..b9921644765
> > --- /dev/null
> > +++ b/drivers/pci/pcie_dw_imx8.c
> > @@ -0,0 +1,348 @@
> > +// SPDX-License-Identifier: GPL-2.0+
> > +/*
> > + * Copyright (C) 2024 Linaro Ltd.
> > + *
> > + * Author: Sumit Garg <sumit.garg at linaro.org>
> > + */
> > +
> > +#include <asm/io.h>
> > +#include <asm-generic/gpio.h>
> > +#include <clk.h>
> > +#include <dm.h>
> > +#include <dm/device_compat.h>
> > +#include <generic-phy.h>
> > +#include <linux/bitops.h>
> > +#include <linux/delay.h>
> > +#include <linux/err.h>
> > +#include <log.h>
> > +#include <pci.h>
> > +#include <regmap.h>
> > +#include <reset.h>
> > +#include <syscon.h>
> > +#include <time.h>
> > +
> > +#include "pcie_dw_common.h"
> > +
> > +#define PCIE_LINK_CAPABILITY 0x7c
> > +#define TARGET_LINK_SPEED_MASK 0xf
> > +#define LINK_SPEED_GEN_1 0x1
> > +#define LINK_SPEED_GEN_2 0x2
> > +#define LINK_SPEED_GEN_3 0x3
> > +
> > +#define PCIE_MISC_CONTROL_1_OFF 0x8bc
> > +#define PCIE_DBI_RO_WR_EN BIT(0)
> > +
> > +#define PCIE_PORT_DEBUG0 0x728
> > +#define PCIE_PORT_DEBUG1 0x72c
> > +#define PCIE_PORT_DEBUG1_LINK_UP BIT(4)
> > +#define PCIE_PORT_DEBUG1_LINK_IN_TRAINING BIT(29)
> > +
> > +#define PCIE_LINK_UP_TIMEOUT_MS 100
> > +
> > +#define IOMUXC_GPR14_OFFSET 0x38
> > +#define IMX8M_GPR_PCIE_CLK_REQ_OVERRIDE_EN BIT(10)
> > +#define IMX8M_GPR_PCIE_CLK_REQ_OVERRIDE BIT(11)
> > +
> > +struct pcie_dw_imx8 {
> > + /* Must be first member of the struct */
> > + struct pcie_dw dw;
> > + struct regmap *iomuxc_gpr;
> > + struct clk pcie;
> > + struct clk pcie_bus;
> > + struct clk pcie_aux;
> > + struct gpio_desc reset_gpio;
> > + struct reset_ctl apps_reset;
> > + struct phy phy;
> > +};
> > +
> > +static void pcie_dw_configure(struct pcie_dw_imx8 *priv, u32 cap_speed)
> > +{
> > + u32 val;
> > +
> > + dw_pcie_dbi_write_enable(&priv->dw, true);
> > +
> > + val = readl(priv->dw.dbi_base + PCIE_LINK_CAPABILITY);
> > + val &= ~TARGET_LINK_SPEED_MASK;
> > + val |= cap_speed;
> > + writel(val, priv->dw.dbi_base + PCIE_LINK_CAPABILITY);
>
> clrsetbits_le32()
Ack.
>
> > +
> > + dw_pcie_dbi_write_enable(&priv->dw, false);
> > +}
> > +
> > +static void imx8_pcie_ltssm_enable(struct pcie_dw_imx8 *priv)
> > +{
> > + reset_deassert(&priv->apps_reset);
> > +}
> > +
> > +static void imx8_pcie_ltssm_disable(struct pcie_dw_imx8 *priv)
> > +{
> > + reset_assert(&priv->apps_reset);
> > +}
> > +
> > +static int is_link_up(struct pcie_dw_imx8 *priv)
> > +{
> > + u32 val;
> > +
> > + val = readl(priv->dw.dbi_base + PCIE_PORT_DEBUG1);
> > +
> > + return ((val & PCIE_PORT_DEBUG1_LINK_UP) &&
> > + (!(val & PCIE_PORT_DEBUG1_LINK_IN_TRAINING)));
> > +}
> > +
> > +static int wait_link_up(struct pcie_dw_imx8 *priv)
> > +{
> > + unsigned long timeout;
> > +
> > + timeout = get_timer(0) + PCIE_LINK_UP_TIMEOUT_MS;
>
> wait_for_bit() or read_poll_timeout()
They won't appropriately fit here as I would like to add delay in
between consecutive polls too...
>
> > + while (!is_link_up(priv)) {
> > + if (get_timer(0) > timeout)
> > + return 0;
> > + mdelay(10);
...here.
> > + };
> > +
> > + return 1;
>
> return -ETIMEDOUT ?
Here 0 represents timeout and 1 represents success condition.
>
> > +}
> > +
> > +static int pcie_link_up(struct pcie_dw_imx8 *priv, u32 cap_speed)
> > +{
> > + if (is_link_up(priv)) {
> > + printf("PCI Link already up before configuration!\n");
> > + return 1;
> > + }
> > +
> > + /* DW pre link configurations */
> > + pcie_dw_configure(priv, cap_speed);
> > +
> > + /* Initiate link training */
> > + imx8_pcie_ltssm_enable(priv);
> > +
> > + /* Check that link was established */
> > + if (!wait_link_up(priv)) {
> > + imx8_pcie_ltssm_disable(priv);
> > + return 0;
> > + }
> > +
> > + return 1;
> > +}
> > +
> > +static int imx8_pcie_assert_core_reset(struct pcie_dw_imx8 *priv)
> > +{
> > + if (dm_gpio_is_valid(&priv->reset_gpio)) {
> > + dm_gpio_set_value(&priv->reset_gpio, 1);
> > + mdelay(20);
> > + }
> > +
> > + return reset_assert(&priv->apps_reset);
> > +}
> > +
> > +static int imx8_pcie_clk_enable(struct pcie_dw_imx8 *priv)
> > +{
> > + int ret;
> > +
> > + ret = clk_enable(&priv->pcie);
>
> Can you use clk_bulk functions here ?
>
Sure, I can try to use them.
> [...]
>
> > +static int imx8_pcie_deassert_core_reset(struct pcie_dw_imx8 *priv)
> > +{
> > + if (dm_gpio_is_valid(&priv->reset_gpio)) {
>
> Invert the match here and return early to reduce indent.
Ack.
>
> > + mdelay(100);
> > + dm_gpio_set_value(&priv->reset_gpio, 0);
> > + /* Wait for 100ms after PERST# deassertion (PCIe r5.0, 6.6.1) */
> > + mdelay(100);
> > + }
> > +
> > + return 0;
> > +}
> > +
> > +static int pcie_dw_imx8_probe(struct udevice *dev)
> > +{
> > + struct pcie_dw_imx8 *priv = dev_get_priv(dev);
> > + struct udevice *ctlr = pci_get_controller(dev);
> > + struct pci_controller *hose = dev_get_uclass_priv(ctlr);
> > + int ret;
> > +
> > + ret = imx8_pcie_assert_core_reset(priv);
> > + if (ret) {
> > + dev_err(dev, "failed to assert core reset\n");
> > + return ret;
> > + }
> > +
> > + ret = imx8_pcie_clk_enable(priv);
> > + if (ret) {
> > + dev_err(dev, "failed to enable clocks\n");
>
> This needs a fail path, else reset remains released on failure here .
>
Ack, I will add that.
-Sumit
> > + return ret;
> > + }
> > +
> > + generic_phy_init(&priv->phy);
> > + generic_phy_power_on(&priv->phy);
> > +
> > + ret = imx8_pcie_deassert_core_reset(priv);
> > + if (ret) {
> > + dev_err(dev, "failed to assert core reset\n");
> > + return ret;
> > + }
> > +
> > + priv->dw.first_busno = dev_seq(dev);
> > + priv->dw.dev = dev;
> > +
> > + pcie_dw_setup_host(&priv->dw);
> > +
> > + if (!pcie_link_up(priv, LINK_SPEED_GEN_1)) {
> > + printf("PCIE-%d: Link down\n", dev_seq(dev));
> > + return -ENODEV;
> > + }
> > +
> > + printf("PCIE-%d: Link up (Gen%d-x%d, Bus%d)\n", dev_seq(dev),
> > + pcie_dw_get_link_speed(&priv->dw),
> > + pcie_dw_get_link_width(&priv->dw),
> > + hose->first_busno);
> > +
> > + pcie_dw_prog_outbound_atu_unroll(&priv->dw, PCIE_ATU_REGION_INDEX0,
> > + PCIE_ATU_TYPE_MEM,
> > + priv->dw.mem.phys_start,
> > + priv->dw.mem.bus_start, priv->dw.mem.size);
> > +
> > + return 0;
> > +}
> > +
> > +static int pcie_dw_imx8_remove(struct udevice *dev)
> > +{
> > + struct pcie_dw_imx8 *priv = dev_get_priv(dev);
> > +
> > + imx8_pcie_assert_core_reset(priv);
> > +
> > + return 0;
> > +}
>
> [...]
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