[PATCH v6 2/4] firmware: raspberrypi: Introduce vl805 init routine

[Nicolas Saenz Julienne]

On the Raspberry Pi 4, after a PCI reset, VL805's firmware may either be
loaded directly from an EEPROM or, if not present, by the SoC's
VideCore. The function informs VideCore that VL805 was just reset, or
requests for a probe defer.

Based on Tim Gover's downstream implementation.

Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@xxxxxxx>
Reviewed-by: Florian Fainelli <f.fainelli@xxxxxxxxx>

---
Changes since v4:
 - Inline function definition when RASPBERRYPI_FIRMWARE is not defined

Changes since v1:
 - Move include into .c file and add forward declaration to .h

 drivers/firmware/raspberrypi.c             | 38 ++++++++++++++++++++++
 include/soc/bcm2835/raspberrypi-firmware.h |  7 ++++
 2 files changed, 45 insertions(+)

diff --git a/drivers/firmware/raspberrypi.c b/drivers/firmware/raspberrypi.c
index da26a584dca0..cbb495aff6a0 100644
--- a/drivers/firmware/raspberrypi.c
+++ b/drivers/firmware/raspberrypi.c
@@ -12,6 +12,7 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/slab.h>
+#include <linux/pci.h>
 #include <soc/bcm2835/raspberrypi-firmware.h>
 
 #define MBOX_MSG(chan, data28)		(((data28) & ~0xf) | ((chan) & 0xf))
@@ -286,6 +287,43 @@ struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node)
 }
 EXPORT_SYMBOL_GPL(rpi_firmware_get);
 
+/*
+ * On the Raspberry Pi 4, after a PCI reset, VL805's firmware may either be
+ * loaded directly from an EEPROM or, if not present, by the SoC's VideCore.
+ * Inform VideCore that VL805 was just reset, or defer xhci's probe if not yet
+ * joinable trough the mailbox interface.
+ */
+int rpi_firmware_init_vl805(struct pci_dev *pdev)
+{
+	struct device_node *fw_np;
+	struct rpi_firmware *fw;
+	u32 dev_addr;
+	int ret;
+
+	fw_np = of_find_compatible_node(NULL, NULL,
+					"raspberrypi,bcm2835-firmware");
+	if (!fw_np)
+		return 0;
+
+	fw = rpi_firmware_get(fw_np);
+	of_node_put(fw_np);
+	if (!fw)
+		return -EPROBE_DEFER;
+
+	dev_addr = pdev->bus->number << 20 | PCI_SLOT(pdev->devfn) << 15 |
+		   PCI_FUNC(pdev->devfn) << 12;
+
+	ret = rpi_firmware_property(fw, RPI_FIRMWARE_NOTIFY_XHCI_RESET,
+				    &dev_addr, sizeof(dev_addr));
+	if (ret)
+		return ret;
+
+	dev_dbg(&pdev->dev, "loaded Raspberry Pi's VL805 firmware\n");
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(rpi_firmware_init_vl805);
+
 static const struct of_device_id rpi_firmware_of_match[] = {
 	{ .compatible = "raspberrypi,bcm2835-firmware", },
 	{},
diff --git a/include/soc/bcm2835/raspberrypi-firmware.h b/include/soc/bcm2835/raspberrypi-firmware.h
index cc9cdbc66403..3025aca3c358 100644
--- a/include/soc/bcm2835/raspberrypi-firmware.h
+++ b/include/soc/bcm2835/raspberrypi-firmware.h
@@ -10,6 +10,7 @@
 #include <linux/of_device.h>
 
 struct rpi_firmware;
+struct pci_dev;
 
 enum rpi_firmware_property_status {
 	RPI_FIRMWARE_STATUS_REQUEST = 0,
@@ -141,6 +142,7 @@ int rpi_firmware_property(struct rpi_firmware *fw,
 int rpi_firmware_property_list(struct rpi_firmware *fw,
 			       void *data, size_t tag_size);
 struct rpi_firmware *rpi_firmware_get(struct device_node *firmware_node);
+int rpi_firmware_init_vl805(struct pci_dev *pdev);
 #else
 static inline int rpi_firmware_property(struct rpi_firmware *fw, u32 tag,
 					void *data, size_t len)
@@ -158,6 +160,11 @@ static inline struct rpi_firmware *rpi_firmware_get(struct device_node *firmware
 {
 	return NULL;
 }
+
+static inline int rpi_firmware_init_vl805(struct pci_dev *pdev)
+{
+	return 0;
+}
 #endif
 
 #endif /* __SOC_RASPBERRY_FIRMWARE_H__ */
-- 
2.25.1