[SeaBIOS] [Seabios] [PATCH v2] seabios: restore piix pm config registers after resume

[Marcel Apfelbaum]

On resume, the OS queries the power management event that
caused it. In order to complete this task, it executes some
reads to the piix pm io space. This all happens before the
OS has a chance to restore the PCI config space for devices,
so it is bios's responsibility to make sure the pm IO space
is configured correctly. (During suspend, the piix pm
configuration space is lost).

Note: For 'ordinary' pci devices the config space is
saved by the OS on sleep and restored on resume.

Signed-off-by: Marcel Apfelbaum <marcel.a at redhat.com>
---
v1 -> v2:
 Addressed Kevin O'Connor comments
 - Simplified patch by remembering PM device bdf

Notes:
 - Without this patch the OS gets stuck because it tries repeatedly
   to read/write to pm io space, but the
   memory region is not enabled, so -1 is returned.
 - After resume the OS does not actually use the pm base address
   configured by the bios to get the IO ports, but uses
   the value from the ACPI FADT table actually. However, as a side effect
   of the configuration, the pm-io space is enabled by Qemu and
   the OS can continue the the boot sequence.
 - Bioses used for hardware like coreboot have the same init
   sequence for piix, see enable_pm from src/southbridge/intel/i82371eb/early_pm.c.


 src/fw/pciinit.c | 24 +++++++++++++++++++++---
 src/hw/pci.h     |  1 +
 src/resume.c     |  2 ++
 src/util.h       |  1 +
 4 files changed, 25 insertions(+), 3 deletions(-)

diff --git a/src/fw/pciinit.c b/src/fw/pciinit.c
index a24b8ff..11c92ae 100644
--- a/src/fw/pciinit.c
+++ b/src/fw/pciinit.c
@@ -230,10 +230,8 @@ static void apple_macio_setup(struct pci_device *pci, void *arg)
     pci_set_io_region_addr(pci, 0, 0x80800000, 0);
 }
 
-/* PIIX4 Power Management device (for ACPI) */
-static void piix4_pm_setup(struct pci_device *pci, void *arg)
+static void piix4_pm_config_setup(u16 bdf)
 {
-    u16 bdf = pci->bdf;
     // acpi sci is hardwired to 9
     pci_config_writeb(bdf, PCI_INTERRUPT_LINE, 9);
 
@@ -241,6 +239,15 @@ static void piix4_pm_setup(struct pci_device *pci, void *arg)
     pci_config_writeb(bdf, 0x80, 0x01); /* enable PM io space */
     pci_config_writel(bdf, 0x90, PORT_SMB_BASE | 1);
     pci_config_writeb(bdf, 0xd2, 0x09); /* enable SMBus io space */
+}
+
+static int PiixPmBDF = -1;
+
+/* PIIX4 Power Management device (for ACPI) */
+static void piix4_pm_setup(struct pci_device *pci, void *arg)
+{
+    PiixPmBDF = pci->bdf;
+    piix4_pm_config_setup(pci->bdf);
 
     acpi_pm1a_cnt = PORT_ACPI_PM_BASE + 0x04;
     pmtimer_setup(PORT_ACPI_PM_BASE + 0x08);
@@ -295,6 +302,17 @@ static const struct pci_device_id pci_device_tbl[] = {
     PCI_DEVICE_END,
 };
 
+void pci_resume(void)
+{
+    if (!CONFIG_QEMU) {
+        return;
+    }
+
+    if (PiixPmBDF >= 0) {
+        piix4_pm_config_setup(PiixPmBDF);
+    }
+}
+
 static void pci_bios_init_device(struct pci_device *pci)
 {
     u16 bdf = pci->bdf;
diff --git a/src/hw/pci.h b/src/hw/pci.h
index 9c7351d..17689a8 100644
--- a/src/hw/pci.h
+++ b/src/hw/pci.h
@@ -66,6 +66,7 @@ extern u64 pcimem64_start, pcimem64_end;
 extern struct hlist_head PCIDevices;
 extern int MaxPCIBus;
 int pci_probe_host(void);
+void pci_resume(void);
 void pci_probe_devices(void);
 static inline u32 pci_classprog(struct pci_device *pci) {
     return (pci->class << 8) | pci->prog_if;
diff --git a/src/resume.c b/src/resume.c
index d69429c..9ad2e4f 100644
--- a/src/resume.c
+++ b/src/resume.c
@@ -101,6 +101,8 @@ s3_resume(void)
     pic_setup();
     smm_setup();
 
+    pci_resume();
+
     s3_resume_vga();
 
     make_bios_readonly();
diff --git a/src/util.h b/src/util.h
index 1b7d525..3f53f4d 100644
--- a/src/util.h
+++ b/src/util.h
@@ -28,6 +28,7 @@ void boot_add_cbfs(void *data, const char *desc, int prio);
 void interactive_bootmenu(void);
 void bcv_prepboot(void);
 struct pci_device;
+void pci_resume(void);
 int bootprio_find_pci_device(struct pci_device *pci);
 int bootprio_find_scsi_device(struct pci_device *pci, int target, int lun);
 int bootprio_find_ata_device(struct pci_device *pci, int chanid, int slave);
-- 
1.8.3.1