On 11.03.2015 16:37, Rob Herring wrote:
On Wed, Mar 11, 2015 at 9:12 AM, Tomasz Nowicki
<tomasz.nowicki@xxxxxxxxxx> wrote:
Architectures which want to take advantage of ECAM generic goodness
This is not necessarily an architecture decision. It is likely per host.
Right, good point.
should select CONFIG_PCI_ECAM_GENERIC. Otherwise, like x86 32bits machines,
are obligated to provide own low-level ECAM calls.
Signed-off-by: Tomasz Nowicki <tomasz.nowicki@xxxxxxxxxx>
---
[...]
diff --git a/drivers/pci/ecam.c b/drivers/pci/ecam.c
index c588234..796b6e7 100644
--- a/drivers/pci/ecam.c
+++ b/drivers/pci/ecam.c
@@ -23,6 +23,119 @@ static DEFINE_MUTEX(pci_mmcfg_lock);
LIST_HEAD(pci_mmcfg_list);
+#ifdef CONFIG_GENERIC_PCI_ECAM
+static char __iomem *pci_dev_base(unsigned int seg, unsigned int bus,
+ unsigned int devfn)
+{
+ struct pci_mmcfg_region *cfg = pci_mmconfig_lookup(seg, bus);
+
+ if (cfg && cfg->virt)
+ return cfg->virt + (PCI_MMCFG_BUS_OFFSET(bus) | (devfn << 12));
+ return NULL;
+}
+
+int pci_mmcfg_read(unsigned int seg, unsigned int bus,
+ unsigned int devfn, int reg, int len, u32 *value)
+{
+ char __iomem *addr;
+
+ /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
+ if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095))) {
+err: *value = -1;
+ return -EINVAL;
+ }
+
+ rcu_read_lock();
What is the purpose of the rcu lock other than the old implementation had it?
Read/write calls consist on lookup RCU list (with MMCONFIG regions) and
then corresponding operation. It is possible to hotplug another pci root
bridge which leads to RCU list modification.
+ addr = pci_dev_base(seg, bus, devfn);
The .map_bus op provides the same function if you restructure to use
the generic accessors.
As you noticed, pci_mmcfg_{read,write} and
pci_generic_config_{read,write} prototypes are different.
int pci_mmcfg_read(unsigned int seg, unsigned int bus,
unsigned int devfn, int reg, int len, u32 *value);
vs
int pci_generic_config_read(struct pci_bus *bus, unsigned int devfn,
int where, int size, u32 *val);
This is because pci_mmcfg_{read,write} can be used before pci root
bridge initialization (while we have no struct pci_bus *bus) inside of
ACPICA code (osl.c --> acpi_os_read_pci_configuration())
For that reason, I decide to create ECAM related new accessors which do
not depend on host bridge presence. In other words,
pci_generic_config_{read,write} can be built on pci_mmcfg_{read,write}
but not the other way around.
In the light of above, I could not used .map_bus. I might not see a
nicer way to solve that so any opinion/suggestion very appreciated :)
+ if (!addr) {
+ rcu_read_unlock();
+ goto err;
+ }
+
+ *value = pci_mmio_read(len, addr + reg);
+ rcu_read_unlock();
+
+ return 0;
+}
+
+int pci_mmcfg_write(unsigned int seg, unsigned int bus,
+ unsigned int devfn, int reg, int len, u32 value)
+{
+ char __iomem *addr;
+
+ /* Why do we have this when nobody checks it. How about a BUG()!? -AK */
+ if (unlikely((bus > 255) || (devfn > 255) || (reg > 4095)))
+ return -EINVAL;
+
+ rcu_read_lock();
+ addr = pci_dev_base(seg, bus, devfn);
+ if (!addr) {
+ rcu_read_unlock();
+ return -EINVAL;
+ }
+
+ pci_mmio_write(len, addr + reg, value);
+ rcu_read_unlock();
+
+ return 0;
+}
+
+static void __iomem *mcfg_ioremap(struct pci_mmcfg_region *cfg)
+{
+ void __iomem *addr;
+ u64 start, size;
+ int num_buses;
+
+ start = cfg->address + PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
+ num_buses = cfg->end_bus - cfg->start_bus + 1;
+ size = PCI_MMCFG_BUS_OFFSET(num_buses);
+ addr = ioremap_nocache(start, size);
+ if (addr)
+ addr -= PCI_MMCFG_BUS_OFFSET(cfg->start_bus);
+ return addr;
+}
+
+int __init pci_mmcfg_arch_init(void)
Where would this be called for the case of the generic host and using DT?
I focused on sharing the code in ACPI context and did not consider DT. I
think we can improve that code as next steps.
Tomasz
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