thunderbolt: Add support for NHI mailbox

The host controller includes two sets of registers that are used to
communicate with the firmware. Add functions that can be used to access
these registers.

This code is based on the work done by Amir Levy and Michael Jamet.

Signed-off-by: Michael Jamet <michael.jamet@intel.com>
Signed-off-by: Mika Westerberg <mika.westerberg@linux.intel.com>
Reviewed-by: Yehezkel Bernat <yehezkel.bernat@intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Andreas Noever <andreas.noever@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/thunderbolt/nhi.c

@@ -14,6 +14,7 @@
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/dmi.h>
+#include <linux/delay.h>
 
 #include "nhi.h"
 #include "nhi_regs.h"
@@ -28,6 +29,8 @@
 #define MSIX_MIN_VECS		6
 #define MSIX_MAX_VECS		16
 
+#define NHI_MAILBOX_TIMEOUT	500 /* ms */
+
 static int ring_interrupt_index(struct tb_ring *ring)
 {
 	int bit = ring->hop;
@@ -525,6 +528,61 @@ void ring_free(struct tb_ring *ring)
 	kfree(ring);
 }
 
+/**
+ * nhi_mailbox_cmd() - Send a command through NHI mailbox
+ * @nhi: Pointer to the NHI structure
+ * @cmd: Command to send
+ * @data: Data to be send with the command
+ *
+ * Sends mailbox command to the firmware running on NHI. Returns %0 in
+ * case of success and negative errno in case of failure.
+ */
+int nhi_mailbox_cmd(struct tb_nhi *nhi, enum nhi_mailbox_cmd cmd, u32 data)
+{
+	ktime_t timeout;
+	u32 val;
+
+	iowrite32(data, nhi->iobase + REG_INMAIL_DATA);
+
+	val = ioread32(nhi->iobase + REG_INMAIL_CMD);
+	val &= ~(REG_INMAIL_CMD_MASK | REG_INMAIL_ERROR);
+	val |= REG_INMAIL_OP_REQUEST | cmd;
+	iowrite32(val, nhi->iobase + REG_INMAIL_CMD);
+
+	timeout = ktime_add_ms(ktime_get(), NHI_MAILBOX_TIMEOUT);
+	do {
+		val = ioread32(nhi->iobase + REG_INMAIL_CMD);
+		if (!(val & REG_INMAIL_OP_REQUEST))
+			break;
+		usleep_range(10, 20);
+	} while (ktime_before(ktime_get(), timeout));
+
+	if (val & REG_INMAIL_OP_REQUEST)
+		return -ETIMEDOUT;
+	if (val & REG_INMAIL_ERROR)
+		return -EIO;
+
+	return 0;
+}
+
+/**
+ * nhi_mailbox_mode() - Return current firmware operation mode
+ * @nhi: Pointer to the NHI structure
+ *
+ * The function reads current firmware operation mode using NHI mailbox
+ * registers and returns it to the caller.
+ */
+enum nhi_fw_mode nhi_mailbox_mode(struct tb_nhi *nhi)
+{
+	u32 val;
+
+	val = ioread32(nhi->iobase + REG_OUTMAIL_CMD);
+	val &= REG_OUTMAIL_CMD_OPMODE_MASK;
+	val >>= REG_OUTMAIL_CMD_OPMODE_SHIFT;
+
+	return (enum nhi_fw_mode)val;
+}
+
 static void nhi_interrupt_work(struct work_struct *work)
 {
 	struct tb_nhi *nhi = container_of(work, typeof(*nhi), interrupt_work);

drivers/thunderbolt/nhi.h

@@ -143,6 +143,22 @@ static inline int ring_tx(struct tb_ring *ring, struct ring_frame *frame)
 	return __ring_enqueue(ring, frame);
 }
 
+enum nhi_fw_mode {
+	NHI_FW_SAFE_MODE,
+	NHI_FW_AUTH_MODE,
+	NHI_FW_EP_MODE,
+	NHI_FW_CM_MODE,
+};
+
+enum nhi_mailbox_cmd {
+	NHI_MAILBOX_SAVE_DEVS = 0x05,
+	NHI_MAILBOX_DRV_UNLOADS = 0x07,
+	NHI_MAILBOX_ALLOW_ALL_DEVS = 0x23,
+};
+
+int nhi_mailbox_cmd(struct tb_nhi *nhi, enum nhi_mailbox_cmd cmd, u32 data);
+enum nhi_fw_mode nhi_mailbox_mode(struct tb_nhi *nhi);
+
 /*
  * PCI IDs used in this driver from Win Ridge forward. There is no
  * need for the PCI quirk anymore as we will use ICM also on Apple

drivers/thunderbolt/nhi_regs.h

@@ -107,4 +107,15 @@ struct ring_desc {
 #define REG_DMA_MISC			0x39864
 #define REG_DMA_MISC_INT_AUTO_CLEAR     BIT(2)
 
+#define REG_INMAIL_DATA			0x39900
+
+#define REG_INMAIL_CMD			0x39904
+#define REG_INMAIL_CMD_MASK		GENMASK(7, 0)
+#define REG_INMAIL_ERROR		BIT(30)
+#define REG_INMAIL_OP_REQUEST		BIT(31)
+
+#define REG_OUTMAIL_CMD			0x3990c
+#define REG_OUTMAIL_CMD_OPMODE_SHIFT	8
+#define REG_OUTMAIL_CMD_OPMODE_MASK	GENMASK(11, 8)
+
 #endif