drivers/siemens/nc_fpga: Add POST code over PCI

So far POST codes were mapped on IO port 0x80 inside the NC FPGA which
was connected via the LPC bus to the host CPU. On recent x86 generations
the LPC bus was replaced with eSPI and not all Siemens boards have the
eSPI routed to the NC FPGA. In order to have POST codes visible on those
boards the display is accessible via PCI in addition.
This patch adds the feature of sending the POST codes to the NC FPGA via
a PCI mapped register.

Change-Id: Ie15686de49cface17830365d78fe7c54cce183a0
Signed-off-by: Werner Zeh <werner.zeh@siemens.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59346
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Mario Scheithauer <mario.scheithauer@siemens.com>

src/drivers/siemens/nc_fpga/Kconfig

@@ -5,3 +5,8 @@ config DRIVER_SIEMENS_NC_FPGA
 config NC_FPGA_NOTIFY_CB_READY
 	bool
 	default n
+
+config NC_FPGA_POST_CODE
+	bool
+	default n
+	select EARLY_PCI_BRIDGE

src/drivers/siemens/nc_fpga/Makefile.inc

@@ -1,3 +1,9 @@
 ## SPDX-License-Identifier: GPL-2.0-only
 
 ramstage-$(CONFIG_DRIVER_SIEMENS_NC_FPGA) += nc_fpga.c
+
+all-$(CONFIG_NC_FPGA_POST_CODE) += nc_fpga_early.c
+
+ifeq ($(CONFIG_NC_FPGA_POST_CODE),y)
+CPPFLAGS_common += -I$(src)/drivers/siemens/nc_fpga
+endif

src/drivers/siemens/nc_fpga/nc_fpga.c

@@ -142,9 +142,21 @@ static void set_fw_done(void *unused)
 BOOT_STATE_INIT_ENTRY(BS_PAYLOAD_BOOT, BS_ON_ENTRY, set_fw_done, NULL);
 #endif
 
+static void nc_fpga_set_resources(struct device *dev)
+{
+	pci_dev_set_resources(dev);
+
+	if (CONFIG(NC_FPGA_POST_CODE)) {
+		/* Re-initialize base address after set_resources for POST display
+		   to work properly.*/
+		nc_fpga_remap(pci_read_config32(dev, PCI_BASE_ADDRESS_0) & ~0xf);
+	}
+}
+
+
 static struct device_operations nc_fpga_ops  = {
 	.read_resources   = pci_dev_read_resources,
-	.set_resources    = pci_dev_set_resources,
+	.set_resources    = nc_fpga_set_resources,
 	.enable_resources = pci_dev_enable_resources,
 	.init             = nc_fpga_init,
 };

src/drivers/siemens/nc_fpga/nc_fpga.h

@@ -17,6 +17,7 @@
 #define  NC_DIAG_FW_DONE		0x10000
 #define NC_BL_BRIGHTNESS_OFFSET		0x88
 #define NC_BL_PWM_OFFSET		0x8C
+#define NC_FPGA_POST_OFFSET		0xE0
 #define NC_FANMON_CTRL_OFFSET		0x400
 
 #define MAX_NUM_SENSORS			8
@@ -58,4 +59,7 @@ typedef struct {
 	uint32_t	fanmon;
 } __packed fan_ctrl_t;
 
+void nc_fpga_post(uint8_t value);
+void nc_fpga_remap(uint32_t new_mmio);
+
 #endif /* _SIEMENS_NC_FPGA_H_ */

src/drivers/siemens/nc_fpga/nc_fpga_early.c

@@ -0,0 +1,49 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+#include <arch/mmio.h>
+#include <device/pci.h>
+#include <device/pci_def.h>
+#include <device/pci_ids.h>
+#include <device/pci_ops.h>
+#include <types.h>
+
+#include "nc_fpga.h"
+
+static DEVTREE_CONST uint32_t fpga_bar = CONFIG_EARLY_PCI_MMIO_BASE;
+static bool nc_fpga_present = false;
+
+int pci_early_device_probe(u8 bus, u8 dev, u32 mmio_base)
+{
+	pci_devfn_t pci_dev = PCI_DEV(bus, dev, 0);
+	uint32_t id = pci_s_read_config32(pci_dev, PCI_VENDOR_ID);
+
+	if (id != (0x4091 << 16 | PCI_VENDOR_ID_SIEMENS))
+		return -1;
+
+	/* Setup base address for BAR0. */
+	pci_s_write_config32(pci_dev, PCI_BASE_ADDRESS_0, mmio_base);
+	/* Enable memory access for pci_dev. */
+	u16 reg16 = pci_s_read_config16(pci_dev, PCI_COMMAND);
+	reg16 |= PCI_COMMAND_MEMORY;
+	pci_s_write_config16(pci_dev, PCI_COMMAND, reg16);
+	nc_fpga_present = true;
+
+	return 0;
+}
+
+void nc_fpga_remap(uint32_t new_mmio)
+{
+#if ENV_RAMSTAGE
+	fpga_bar = new_mmio;
+#endif
+}
+
+void nc_fpga_post(uint8_t value)
+{
+	/* The function pci_earyl_device_probe is called in bootblock and romstage. Make sure
+	   that in these stages the initialization code was successful before the POST code
+	   value is written to the register. */
+	if ((ENV_BOOTBLOCK || ENV_ROMSTAGE) && nc_fpga_present == false)
+		return;
+	write32((void *)(fpga_bar + NC_FPGA_POST_OFFSET), value);
+}