[PATCH] ipq40xx: add PCIe magic hack to improve VRX518 compatibility
Jan Hoffmann
jan at 3e8.eu
Mon Jan 30 14:40:20 PST 2023
Some VRX518 modems fail to initialize properly with the error message
"dc_ep_clk_on failed". As a result, the DSL data path doesn't work.
This hack, which is based on code from the FRITZ!Box 7530 GPL archive,
fixes the issue. It changes the PCIe vendor/device ID to values matching
a Lantiq SoC. It also appears to emulate a Lantiq CPU ID register for
connected PCIe devices, by remapping the matching address area to a
specially crafted buffer using the address translation unit.
The hack is only active if the "avm,host_magic" property is specified in
the device tree, so this shouldn't affect any devices other than
FRITZ!Box 7530/7520.
Signed-off-by: Jan Hoffmann <jan at 3e8.eu>
---
.../boot/dts/qcom-ipq4019-fritzbox-7530.dts | 2 +
.../997-pcie-qcom-host-magic.patch | 215 ++++++++++++++++++
2 files changed, 217 insertions(+)
create mode 100644 target/linux/ipq40xx/patches-5.15/997-pcie-qcom-host-magic.patch
diff --git a/target/linux/ipq40xx/files/arch/arm/boot/dts/qcom-ipq4019-fritzbox-7530.dts b/target/linux/ipq40xx/files/arch/arm/boot/dts/qcom-ipq4019-fritzbox-7530.dts
index 336da52f2724..bc167616d3dc 100644
--- a/target/linux/ipq40xx/files/arch/arm/boot/dts/qcom-ipq4019-fritzbox-7530.dts
+++ b/target/linux/ipq40xx/files/arch/arm/boot/dts/qcom-ipq4019-fritzbox-7530.dts
@@ -306,6 +306,8 @@
perst-gpio = <&tlmm 38 GPIO_ACTIVE_LOW>;
wake-gpio = <&tlmm 50 GPIO_ACTIVE_LOW>;
+ avm,host_magic;
+
bridge at 0,0 {
reg = <0x00000000 0 0 0 0>;
#address-cells = <3>;
diff --git a/target/linux/ipq40xx/patches-5.15/997-pcie-qcom-host-magic.patch b/target/linux/ipq40xx/patches-5.15/997-pcie-qcom-host-magic.patch
new file mode 100644
index 000000000000..f427bccd2f4a
--- /dev/null
+++ b/target/linux/ipq40xx/patches-5.15/997-pcie-qcom-host-magic.patch
@@ -0,0 +1,215 @@
+This hack is based on code from the FRITZ!Box 7530 GPL archive for
+firmware version 07.50.
+
+If the device tree contains the "avm,host_magic" property, it changes
+the PCIe vendor/device ID to the values from Lantiq GRX500 SoCs. It also
+programs the ATU to present a buffer containing a magic value to PCIe
+devices. This appears to emulate a Lantiq CPU ID register.
+
+Without this hack, some VRX518 modems fail to initialize properly (error
+"dc_ep_clk_on failed"), and the DSL data path doesn't work.
+--- a/drivers/pci/controller/dwc/pcie-qcom.c
++++ b/drivers/pci/controller/dwc/pcie-qcom.c
+@@ -27,6 +27,7 @@
+ #include <linux/reset.h>
+ #include <linux/slab.h>
+ #include <linux/types.h>
++#include <linux/version.h>
+
+ #include "../../pci.h"
+ #include "pcie-designware.h"
+@@ -102,6 +103,8 @@
+
+ #define QCOM_PCIE_CRC8_POLYNOMIAL (BIT(2) | BIT(1) | BIT(0))
+
++#define PCIE_MAGIC_SIZE 0x10000
++
+ struct qcom_pcie_resources_2_1_0 {
+ struct clk_bulk_data clks[QCOM_PCIE_2_1_0_MAX_CLOCKS];
+ struct reset_control *pci_reset;
+@@ -197,6 +200,8 @@ struct qcom_pcie {
+ struct phy *phy;
+ struct gpio_desc *reset;
+ const struct qcom_pcie_ops *ops;
++ void *magic_cpu_addr;
++ dma_addr_t magic_dma_handle;
+ };
+
+ #define to_qcom_pcie(x) dev_get_drvdata((x)->dev)
+@@ -1388,8 +1393,141 @@ err_deinit:
+ return ret;
+ }
+
++static int qcom_pcie_magic_prog_atu(struct qcom_pcie *pcie,
++ u32 addr, u32 limit, u32 phys)
++{
++ struct dw_pcie *pci = pcie->pci;
++ struct device *dev = pci->dev;
++ u32 retries, val;
++ int index;
++
++ if (!pci->num_ib_windows) {
++ dev_err(dev, "No inbound ATU window available for magic\n");
++ return -1;
++ }
++
++ /*
++ * Use highest window index and reduce window count so the driver
++ * won't overwrite the entry later.
++ */
++ index = --pci->num_ib_windows;
++
++#if LINUX_VERSION_CODE < KERNEL_VERSION(6,0,0)
++ if (pci->iatu_unroll_enabled) {
++ dev_err(dev, "Programming ATU for magic not implemented for this hardware\n");
++ return -1;
++ }
++
++ dw_pcie_writel_dbi(pci, PCIE_ATU_VIEWPORT,
++ PCIE_ATU_REGION_INBOUND | index);
++
++ dw_pcie_writel_dbi(pci, PCIE_ATU_LOWER_BASE, addr);
++ dw_pcie_writel_dbi(pci, PCIE_ATU_UPPER_BASE, 0);
++ dw_pcie_writel_dbi(pci, PCIE_ATU_LIMIT, limit);
++ dw_pcie_writel_dbi(pci, PCIE_ATU_LOWER_TARGET, phys);
++ dw_pcie_writel_dbi(pci, PCIE_ATU_UPPER_TARGET, 0);
++
++ dw_pcie_writel_dbi(pci, PCIE_ATU_CR1, PCIE_ATU_TYPE_MEM);
++ dw_pcie_writel_dbi(pci, PCIE_ATU_CR2, PCIE_ATU_ENABLE);
++
++ for (retries = 0; retries < LINK_WAIT_MAX_IATU_RETRIES; retries++) {
++ val = dw_pcie_readl_dbi(pci, PCIE_ATU_CR2);
++ if (val & PCIE_ATU_ENABLE)
++ return 0;
++
++ mdelay(LINK_WAIT_IATU);
++ }
++#else
++ dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LOWER_BASE, addr);
++ dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_UPPER_BASE, 0);
++ dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LIMIT, limit);
++ dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_LOWER_TARGET, phys);
++ dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_UPPER_TARGET, 0);
++
++ dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_REGION_CTRL1,
++ PCIE_ATU_TYPE_MEM);
++ dw_pcie_writel_atu_ib(pci, index, PCIE_ATU_REGION_CTRL2,
++ PCIE_ATU_ENABLE);
++
++ for (retries = 0; retries < LINK_WAIT_MAX_IATU_RETRIES; retries++) {
++ val = dw_pcie_readl_atu_ib(pci, index, PCIE_ATU_REGION_CTRL2);
++ if (val & PCIE_ATU_ENABLE)
++ return 0;
++
++ mdelay(LINK_WAIT_IATU);
++ }
++#endif
++
++ dev_err(dev, "Failed to program ATU for magic\n");
++ return -1;
++}
++
++static void qcom_pcie_magic_deinit(struct qcom_pcie *pcie)
++{
++ struct dw_pcie *pci = pcie->pci;
++ struct device *dev = pci->dev;
++
++ if (pcie->magic_cpu_addr) {
++ dma_free_coherent(dev, PCIE_MAGIC_SIZE,
++ pcie->magic_cpu_addr,
++ pcie->magic_dma_handle);
++
++ pcie->magic_cpu_addr = NULL;
++ }
++}
++
++static void qcom_pcie_magic_init(struct qcom_pcie *pcie)
++{
++ struct dw_pcie *pci = pcie->pci;
++ struct device *dev = pci->dev;
++ u32 *virt;
++ u32 phys;
++ int ret;
++
++ if (!of_property_read_bool(dev->of_node, "avm,host_magic"))
++ return;
++
++ dev_info(dev, "Applying PCIe host magic\n");
++
++ virt = dma_alloc_coherent(dev, PCIE_MAGIC_SIZE, &phys, GFP_ATOMIC);
++ BUG_ON(virt == NULL);
++
++ pcie->magic_cpu_addr = virt;
++ pcie->magic_dma_handle = phys;
++
++ /*
++ * This value is the manufacturer ID of Lantiq. The address where
++ * it will be visible for the PCIe device matches the location of
++ * CPU ID registers on Lantiq SocS (MPS base address is 0x1f107000).
++ */
++ virt[0x7340/4] = 0x389 << 5;
++
++ /* Make it visible to PCIe devices using address translation unit */
++ ret = qcom_pcie_magic_prog_atu(pcie, 0x1f100000, 0x1f10ffff, phys);
++
++ dw_pcie_dbi_ro_wr_en(pci);
++
++ /* Set vendor/device ID of GRX500 PCIe host */
++ dw_pcie_writew_dbi(pci, PCI_VENDOR_ID, 0x1bef);
++ dw_pcie_writew_dbi(pci, PCI_DEVICE_ID, 0x0030);
++
++ dw_pcie_dbi_ro_wr_dis(pci);
++
++ if (ret)
++ qcom_pcie_magic_deinit(pcie);
++}
++
++static void qcom_pcie_atu_hack(struct pcie_port *pp)
++{
++ struct dw_pcie *pci = to_dw_pcie_from_pp(pp);
++ struct qcom_pcie *pcie = to_qcom_pcie(pci);
++
++ qcom_pcie_magic_init(pcie);
++}
++
+ static const struct dw_pcie_host_ops qcom_pcie_dw_ops = {
+ .host_init = qcom_pcie_host_init,
++ .atu_hack = qcom_pcie_atu_hack,
+ };
+
+ /* Qcom IP rev.: 2.1.0 Synopsys IP rev.: 4.01a */
+@@ -1536,6 +1674,7 @@ static int qcom_pcie_probe(struct platfo
+
+ err_phy_exit:
+ phy_exit(pcie->phy);
++ qcom_pcie_magic_deinit(pcie);
+ err_pm_runtime_put:
+ pm_runtime_put(dev);
+ pm_runtime_disable(dev);
+--- a/drivers/pci/controller/dwc/pcie-designware-host.c
++++ b/drivers/pci/controller/dwc/pcie-designware-host.c
+@@ -400,6 +400,14 @@ int dw_pcie_host_init(struct pcie_port *
+ }
+ dw_pcie_iatu_detect(pci);
+
++ /*
++ * This needs to be called after ATU detection, but before the driver
++ * sets up any ATU entries, to avoid any ATU entry programmed in the
++ * hack being overwritten by the driver later.
++ */
++ if (pp->ops->atu_hack)
++ pp->ops->atu_hack(pp);
++
+ dw_pcie_setup_rc(pp);
+
+ if (!dw_pcie_link_up(pci) && pci->ops && pci->ops->start_link) {
+--- a/drivers/pci/controller/dwc/pcie-designware.h
++++ b/drivers/pci/controller/dwc/pcie-designware.h
+@@ -174,6 +174,7 @@ enum dw_pcie_device_mode {
+
+ struct dw_pcie_host_ops {
+ int (*host_init)(struct pcie_port *pp);
++ void (*atu_hack)(struct pcie_port *pp);
+ int (*msi_host_init)(struct pcie_port *pp);
+ };
+
--
2.39.1
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