[PATCH v2 2/2] PCI: designware-ep: Fix the access to DBI/iATU registers before enabling controller

From: Kunihiko Hayashi
Date: Wed Sep 01 2021 - 01:16:25 EST


The driver using core_init_notifier, e.g. pcie-tegra194.c, runs according
to the following sequence:

probe()
dw_pcie_ep_init()

bind()
dw_pcie_ep_start()
enable_irq()

(interrupt occurred)
handler()
[enable controller]
dw_pcie_ep_init_complete()
dw_pcie_ep_init_notify()

After receiving an interrupt from RC, the handler enables the controller
and the controller registers can be accessed.
So accessing the registers should do in dw_pcie_ep_init_complete().

Currently dw_pcie_ep_init() has functions dw_iatu_detect() and
dw_pcie_ep_find_capability() that include accesses to DWC registers.
As a result, accessing the registers before enabling the controller,
the access will fail.

The function dw_pcie_ep_init() shouldn't have any access to DWC registers
if the controller is enabled after calling bind(). This moves access codes
to DBI/iATU registers and depending variables from dw_pcie_ep_init() to
dw_pcie_ep_init_complete().

Cc: Xiaowei Bao <xiaowei.bao@xxxxxxx>
Cc: Vidya Sagar <vidyas@xxxxxxxxxx>
Fixes: 6bfc9c3a2c70 ("PCI: designware-ep: Move the function of getting MSI capability forward")
Signed-off-by: Kunihiko Hayashi <hayashi.kunihiko@xxxxxxxxxxxxx>
Acked-by: Om Prakash Singh <omp@xxxxxxxxxx>
Reviewed-by: Vidya Sagar <vidyas@xxxxxxxxxx>
---
drivers/pci/controller/dwc/pcie-designware-ep.c | 81 +++++++++++++------------
1 file changed, 41 insertions(+), 40 deletions(-)

diff --git a/drivers/pci/controller/dwc/pcie-designware-ep.c b/drivers/pci/controller/dwc/pcie-designware-ep.c
index 998b698..00ce83c 100644
--- a/drivers/pci/controller/dwc/pcie-designware-ep.c
+++ b/drivers/pci/controller/dwc/pcie-designware-ep.c
@@ -636,16 +636,56 @@ static unsigned int dw_pcie_ep_find_ext_capability(struct dw_pcie *pci, int cap)
int dw_pcie_ep_init_complete(struct dw_pcie_ep *ep)
{
struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
+ struct dw_pcie_ep_func *ep_func;
+ struct device *dev = pci->dev;
unsigned int offset;
unsigned int nbars;
u8 hdr_type;
+ u8 func_no;
+ void *addr;
u32 reg;
int i;

+ dw_pcie_iatu_detect(pci);
+
+ ep->ib_window_map = devm_kcalloc(dev,
+ BITS_TO_LONGS(pci->num_ib_windows),
+ sizeof(long),
+ GFP_KERNEL);
+ if (!ep->ib_window_map)
+ return -ENOMEM;
+
+ ep->ob_window_map = devm_kcalloc(dev,
+ BITS_TO_LONGS(pci->num_ob_windows),
+ sizeof(long),
+ GFP_KERNEL);
+ if (!ep->ob_window_map)
+ return -ENOMEM;
+
+ addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t),
+ GFP_KERNEL);
+ if (!addr)
+ return -ENOMEM;
+ ep->outbound_addr = addr;
+
+ for (func_no = 0; func_no < ep->epc->max_functions; func_no++) {
+ ep_func = devm_kzalloc(dev, sizeof(*ep_func), GFP_KERNEL);
+ if (!ep_func)
+ return -ENOMEM;
+
+ ep_func->func_no = func_no;
+ ep_func->msi_cap = dw_pcie_ep_find_capability(ep, func_no,
+ PCI_CAP_ID_MSI);
+ ep_func->msix_cap = dw_pcie_ep_find_capability(ep, func_no,
+ PCI_CAP_ID_MSIX);
+
+ list_add_tail(&ep_func->list, &ep->func_list);
+ }
+
hdr_type = dw_pcie_readb_dbi(pci, PCI_HEADER_TYPE) &
PCI_HEADER_TYPE_MASK;
if (hdr_type != PCI_HEADER_TYPE_NORMAL) {
- dev_err(pci->dev,
+ dev_err(dev,
"PCIe controller is not set to EP mode (hdr_type:0x%x)!\n",
hdr_type);
return -EIO;
@@ -674,8 +714,6 @@ EXPORT_SYMBOL_GPL(dw_pcie_ep_init_complete);
int dw_pcie_ep_init(struct dw_pcie_ep *ep)
{
int ret;
- void *addr;
- u8 func_no;
struct resource *res;
struct pci_epc *epc;
struct dw_pcie *pci = to_dw_pcie_from_ep(ep);
@@ -683,7 +721,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
struct platform_device *pdev = to_platform_device(dev);
struct device_node *np = dev->of_node;
const struct pci_epc_features *epc_features;
- struct dw_pcie_ep_func *ep_func;

INIT_LIST_HEAD(&ep->func_list);

@@ -705,8 +742,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
}
}

- dw_pcie_iatu_detect(pci);
-
res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "addr_space");
if (!res)
return -EINVAL;
@@ -714,26 +749,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
ep->phys_base = res->start;
ep->addr_size = resource_size(res);

- ep->ib_window_map = devm_kcalloc(dev,
- BITS_TO_LONGS(pci->num_ib_windows),
- sizeof(long),
- GFP_KERNEL);
- if (!ep->ib_window_map)
- return -ENOMEM;
-
- ep->ob_window_map = devm_kcalloc(dev,
- BITS_TO_LONGS(pci->num_ob_windows),
- sizeof(long),
- GFP_KERNEL);
- if (!ep->ob_window_map)
- return -ENOMEM;
-
- addr = devm_kcalloc(dev, pci->num_ob_windows, sizeof(phys_addr_t),
- GFP_KERNEL);
- if (!addr)
- return -ENOMEM;
- ep->outbound_addr = addr;
-
if (pci->link_gen < 1)
pci->link_gen = of_pci_get_max_link_speed(np);

@@ -750,20 +765,6 @@ int dw_pcie_ep_init(struct dw_pcie_ep *ep)
if (ret < 0)
epc->max_functions = 1;

- for (func_no = 0; func_no < epc->max_functions; func_no++) {
- ep_func = devm_kzalloc(dev, sizeof(*ep_func), GFP_KERNEL);
- if (!ep_func)
- return -ENOMEM;
-
- ep_func->func_no = func_no;
- ep_func->msi_cap = dw_pcie_ep_find_capability(ep, func_no,
- PCI_CAP_ID_MSI);
- ep_func->msix_cap = dw_pcie_ep_find_capability(ep, func_no,
- PCI_CAP_ID_MSIX);
-
- list_add_tail(&ep_func->list, &ep->func_list);
- }
-
if (ep->ops->ep_init)
ep->ops->ep_init(ep);

--
2.7.4