parisc: Add qemu fw_cfg interface

Commit Message

Helge Deller Aug. 14, 2020, 6 p.m. UTC

When running on qemu, SeaBIOS-hppa stores the iomem address for the
emulated fw_cfg port in PAGE0_>pad0[2/3]. Let the Linux driver
auto-configure the fw_cfg interface with it, so that the fw_cfg info
shows up in /sys/firmware/qemu_fw_cfg.

Signed-off-by: Helge Deller <[e-mail]>

Patch

diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
index 8e4c3708773d..ba26d224c653 100644
--- a/arch/parisc/Kconfig
+++ b/arch/parisc/Kconfig
@@ -376,6 +376,7 @@  config KEXEC_FILE

 endmenu

+source "drivers/firmware/Kconfig"

 source "drivers/parisc/Kconfig"

diff --git a/arch/parisc/kernel/inventory.c b/arch/parisc/kernel/inventory.c
index 9298f2285510..7ab2f2a54400 100644
--- a/arch/parisc/kernel/inventory.c
+++ b/arch/parisc/kernel/inventory.c
@@ -19,6 +19,7 @@ 
 #include <linux/init.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
+#include <linux/platform_device.h>
 #include <asm/hardware.h>
 #include <asm/io.h>
 #include <asm/mmzone.h>
@@ -641,4 +642,33 @@  void __init do_device_inventory(void)
 	if (pa_serialize_tlb_flushes)
 		pr_info("Merced bus found: Enable PxTLB serialization.\n");
 #endif
+
+#if defined(CONFIG_FW_CFG_SYSFS)
+	if (running_on_qemu) {
+		struct resource res[3] = {0,};
+		unsigned int base;
+
+		base = ((unsigned long long) PAGE0->pad0[2] << 32)
+			| PAGE0->pad0[3]; /* SeaBIOS stored it here */
+
+		res[0].name = "fw_cfg";
+		res[0].start = base;
+		res[0].end = base + 8 - 1;
+		res[0].flags = IORESOURCE_MEM;
+
+		res[1].name = "ctrl";
+		res[1].start = 0;
+		res[1].flags = IORESOURCE_REG;
+
+		res[2].name = "data";
+		res[2].start = 4;
+		res[2].flags = IORESOURCE_REG;
+
+		if (base) {
+			pr_info("Found qemu fw_cfg interface at %#08x\n", base);
+			platform_device_register_simple("fw_cfg",
+				PLATFORM_DEVID_NONE, res, 3);
+		}
+	}
+#endif
 }
diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index fbd785dd0513..25f51b60194b 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -187,7 +187,7 @@  config RASPBERRYPI_FIRMWARE

 config FW_CFG_SYSFS
 	tristate "QEMU fw_cfg device support in sysfs"
-	depends on SYSFS && (ARM || ARM64 || PPC_PMAC || SPARC || X86)
+	depends on SYSFS && (ARM || ARM64 || PARISC || PPC_PMAC || SPARC || X86)
 	depends on HAS_IOPORT_MAP
 	default n
 	help
diff --git a/drivers/firmware/qemu_fw_cfg.c b/drivers/firmware/qemu_fw_cfg.c
index 6945c3c96637..0078260fbabe 100644
--- a/drivers/firmware/qemu_fw_cfg.c
+++ b/drivers/firmware/qemu_fw_cfg.c
@@ -215,6 +215,9 @@  static void fw_cfg_io_cleanup(void)
 #  define FW_CFG_CTRL_OFF 0x08
 #  define FW_CFG_DATA_OFF 0x00
 #  define FW_CFG_DMA_OFF 0x10
+# elif defined(CONFIG_PARISC)	/* parisc */
+#  define FW_CFG_CTRL_OFF 0x00
+#  define FW_CFG_DATA_OFF 0x04
 # elif (defined(CONFIG_PPC_PMAC) || defined(CONFIG_SPARC32)) /* ppc/mac,sun4m */
 #  define FW_CFG_CTRL_OFF 0x00
 #  define FW_CFG_DATA_OFF 0x02