[PATCH 06/15] PCI: mvebu: Fix support for bus mastering and PCI_COMMAND on emulated bridge

Pali Rohár
2021-11-25T12:50:15Z

According to PCI specifications bits [0:2] of Command Register, this should
be by default disabled on reset. So explicitly disable these bits at early
beginning of driver initialization.

Also remove code which unconditionally enables all 3 bits and let kernel
code (via pci_set_master() function) to handle bus mastering of PCI Bridge
via emulated PCI_COMMAND on emulated bridge.

Adjust existing functions mvebu_pcie_handle_iobase_change() and
mvebu_pcie_handle_membase_change() to handle PCI_IO_BASE and PCI_MEM_BASE
registers correctly even when bus mastering on emulated bridge is disabled.

Signed-off-by: Pali Rohár <pali@kernel.org>
Cc: stable@vger.kernel.org
---
drivers/pci/controller/pci-mvebu.c | 52 ++++++++++++++++++------------
1 file changed, 32 insertions(+), 20 deletions(-)

diff --git a/drivers/pci/controller/pci-mvebu.c b/drivers/pci/controller/pci-mvebu.c
index a3df352d440e..32694763e930 100644
--- a/drivers/pci/controller/pci-mvebu.c
+++ b/drivers/pci/controller/pci-mvebu.c
@@ -226,16 +226,14 @@ static void mvebu_pcie_setup_hw(struct mvebu_pcie_port *port)
{
u32 cmd, mask;

- /* Point PCIe unit MBUS decode windows to DRAM space. */
- mvebu_pcie_setup_wins(port);
-
- /* Master + slave enable. */
+ /* Disable Root Bridge I/O space, memory space and bus mastering. */
cmd = mvebu_readl(port, PCIE_CMD_OFF);
- cmd |= PCI_COMMAND_IO;
- cmd |= PCI_COMMAND_MEMORY;
- cmd |= PCI_COMMAND_MASTER;
+ cmd &= ~(PCI_COMMAND_IO | PCI_COMMAND_MEMORY | PCI_COMMAND_MASTER);
mvebu_writel(port, cmd, PCIE_CMD_OFF);

+ /* Point PCIe unit MBUS decode windows to DRAM space. */
+ mvebu_pcie_setup_wins(port);
+
/* Enable interrupt lines A-D. */
mask = mvebu_readl(port, PCIE_MASK_OFF);
mask |= PCIE_MASK_ENABLE_INTS;
@@ -385,8 +383,7 @@ static void mvebu_pcie_handle_iobase_change(struct mvebu_pcie_port *port)

/* Are the new iobase/iolimit values invalid? */
if (conf->iolimit < conf->iobase ||
- conf->iolimitupper < conf->iobaseupper ||
- !(conf->command & PCI_COMMAND_IO)) {
+ conf->iolimitupper < conf->iobaseupper) {
mvebu_pcie_set_window(port, port->io_target, port->io_attr,
&desired, &port->iowin);
return;
@@ -423,8 +420,7 @@ static void mvebu_pcie_handle_membase_change(struct mvebu_pcie_port *port)
struct pci_bridge_emul_conf *conf = &port->bridge.conf;

/* Are the new membase/memlimit values invalid? */
- if (conf->memlimit < conf->membase ||
- !(conf->command & PCI_COMMAND_MEMORY)) {
+ if (conf->memlimit < conf->membase) {
mvebu_pcie_set_window(port, port->mem_target, port->mem_attr,
&desired, &port->memwin);
return;
@@ -444,6 +440,24 @@ static void mvebu_pcie_handle_membase_change(struct mvebu_pcie_port *port)
&port->memwin);
}

+static pci_bridge_emul_read_status_t
+mvebu_pci_bridge_emul_base_conf_read(struct pci_bridge_emul *bridge,
+ int reg, u32 *value)
+{
+ struct mvebu_pcie_port *port = bridge->data;
+
+ switch (reg) {
+ case PCI_COMMAND:
+ *value = mvebu_readl(port, PCIE_CMD_OFF);
+ break;
+
+ default:
+ return PCI_BRIDGE_EMUL_NOT_HANDLED;
+ }
+
+ return PCI_BRIDGE_EMUL_HANDLED;
+}
+
static pci_bridge_emul_read_status_t
mvebu_pci_bridge_emul_pcie_conf_read(struct pci_bridge_emul *bridge,
int reg, u32 *value)
@@ -498,17 +512,14 @@ mvebu_pci_bridge_emul_base_conf_write(struct pci_bridge_emul *bridge,

switch (reg) {
case PCI_COMMAND:
- {
- if (!mvebu_has_ioport(port))
- conf->command &= ~PCI_COMMAND_IO;
-
- if ((old ^ new) & PCI_COMMAND_IO)
- mvebu_pcie_handle_iobase_change(port);
- if ((old ^ new) & PCI_COMMAND_MEMORY)
- mvebu_pcie_handle_membase_change(port);
+ if (!mvebu_has_ioport(port)) {
+ conf->command = cpu_to_le16(
+ le16_to_cpu(conf->command) & ~PCI_COMMAND_IO);
+ new &= ~PCI_COMMAND_IO;
+ }

+ mvebu_writel(port, new, PCIE_CMD_OFF);
break;
- }

case PCI_IO_BASE:
/*
@@ -575,6 +586,7 @@ mvebu_pci_bridge_emul_pcie_conf_write(struct pci_bridge_emul *bridge,
}

static struct pci_bridge_emul_ops mvebu_pci_bridge_emul_ops = {
+ .read_base = mvebu_pci_bridge_emul_base_conf_read,
.write_base = mvebu_pci_bridge_emul_base_conf_write,
.read_pcie = mvebu_pci_bridge_emul_pcie_conf_read,
.write_pcie = mvebu_pci_bridge_emul_pcie_conf_write,
--
2.20.1