occ: Add support for OPAL-OCC command/response interface

This patch adds support for a shared memory based command/response
interface between OCC and OPAL. In HOMER, there is an OPAL command
buffer and an OCC response buffer which is used to send inband
commands to OCC.

The OPAL-OCC command/response sequence is as follows:

1. Check if both 'OCC Progress' bit in OCC response flag and 'Cmd Ready'
   bit in OPAL command flag are set to zero. If yes then proceed with
   below steps to send a command to OCC.
2. Write the command value, request ID and command specific data
   to the OPAL command buffer.
3. Clear the response flag and set the 'Cmd Ready' bit in OPAL command
   flag to indicate command is ready.
4. OCC will poll the command flag every 4ms to check if 'Cmd Ready' bit
   is set by OPAL. If the bit is set then OCC will set the 'OCC Progress'
   bit.
5. OCC will process the command and write the response to the OCC response
   buffer and set the 'Rsp Ready' bit in the response flag and sends an
   interrupt.
8. OPAL will receive the interrupt and queue the response to the host.

Signed-off-by: Shilpasri G Bhat <shilpa.bhat@linux.vnet.ibm.com>
Reviewed-by: Cyril Bur <cyril.bur@au1.ibm.com>
Signed-off-by: Stewart Smith <stewart@linux.vnet.ibm.com>

2 files changed, 416 insertions, 4 deletions

diff --git a/hw/occ.c b/hw/occ.c
index 7d0d22c..58d9778 100644
--- a/hw/occ.c
+++ b/hw/occ.c
@@ -41,6 +41,9 @@
 #define MAX_P8_CORES			12
 #define MAX_P9_CORES			24
 
+#define MAX_OPAL_CMD_DATA_LENGTH	4090
+#define MAX_OCC_RSP_DATA_LENGTH		8698
+
 /**
  * OCC-OPAL Shared Memory Region
  *
@@ -120,6 +123,87 @@ struct occ_pstate_table {
 } __packed;
 
 /**
+ * OPAL-OCC Command Response Interface
+ *
+ * OPAL-OCC Command Buffer
+ *
+ * ---------------------------------------------------------------------
+ * | OPAL  |  Cmd    | OPAL |	       | Cmd Data | Cmd Data | OPAL    |
+ * | Cmd   | Request | OCC  | Reserved | Length   | Length   | Cmd     |
+ * | Flags |   ID    | Cmd  |	       | (MSB)    | (LSB)    | Data... |
+ * ---------------------------------------------------------------------
+ * |  ….OPAL Command Data up to max of Cmd Data Length 4090 bytes      |
+ * |								       |
+ * ---------------------------------------------------------------------
+ *
+ * OPAL Command Flag
+ *
+ * -----------------------------------------------------------------
+ * | Bit 7 | Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
+ * | (msb) |	   |	   |	   |	   |	   |	   | (lsb) |
+ * -----------------------------------------------------------------
+ * |Cmd    |       |       |       |       |       |       |       |
+ * |Ready  |	   |	   |	   |	   |	   |	   |	   |
+ * -----------------------------------------------------------------
+ *
+ * struct opal_command_buffer -	Defines the layout of OPAL command buffer
+ * @flag:			Provides general status of the command
+ * @request_id:			Token to identify request
+ * @cmd:			Command sent
+ * @data_size:			Command data length
+ * @data:			Command specific data
+ * @spare:			Unused byte
+ */
+struct opal_command_buffer {
+	u8 flag;
+	u8 request_id;
+	u8 cmd;
+	u8 spare;
+	u16 data_size;
+	u8 data[MAX_OPAL_CMD_DATA_LENGTH];
+} __packed;
+
+/**
+ * OPAL-OCC Response Buffer
+ *
+ * ---------------------------------------------------------------------
+ * | OCC   |  Cmd    | OPAL | Response | Rsp Data | Rsp Data | OPAL    |
+ * | Rsp   | Request | OCC  |  Status  | Length   | Length   | Rsp     |
+ * | Flags |   ID    | Cmd  |	       | (MSB)    | (LSB)    | Data... |
+ * ---------------------------------------------------------------------
+ * |  ….OPAL Response Data up to max of Rsp Data Length 8698 bytes     |
+ * |								       |
+ * ---------------------------------------------------------------------
+ *
+ * OCC Response Flag
+ *
+ * -----------------------------------------------------------------
+ * | Bit 7 | Bit 6 | Bit 5 | Bit 4 | Bit 3 | Bit 2 | Bit 1 | Bit 0 |
+ * | (msb) |	   |	   |	   |	   |	   |	   | (lsb) |
+ * -----------------------------------------------------------------
+ * |       |       |       |       |       |       |OCC in  | Rsp  |
+ * |       |	   |	   |	   |	   |	   |progress|Ready |
+ * -----------------------------------------------------------------
+ *
+ * struct occ_response_buffer -	Defines the layout of OCC response buffer
+ * @flag:			Provides general status of the response
+ * @request_id:			Token to identify request
+ * @cmd:			Command requested
+ * @status:			Indicates success/failure status of
+ *				the command
+ * @data_size:			Response data length
+ * @data:			Response specific data
+ */
+struct occ_response_buffer {
+	u8 flag;
+	u8 request_id;
+	u8 cmd;
+	u8 status;
+	u16 data_size;
+	u8 data[MAX_OCC_RSP_DATA_LENGTH];
+} __packed;
+
+/**
  * OCC-OPAL Shared Memory Interface Dynamic Data Vx90
  *
  * struct occ_dynamic_data -	Contains runtime attributes
@@ -136,6 +220,8 @@ struct occ_pstate_table {
  * @max_pwr_cap:		Maximum allowed system power cap in Watts
  * @cur_pwr_cap:		Current system power cap
  * @spare/reserved:		Unused data
+ * @cmd:			Opal Command Buffer
+ * @rsp:			OCC Response Buffer
  */
 struct occ_dynamic_data {
 	u8 occ_state;
@@ -151,7 +237,9 @@ struct occ_dynamic_data {
 	u16 min_pwr_cap;
 	u16 max_pwr_cap;
 	u16 cur_pwr_cap;
-	u64 reserved;
+	u8 pad[112];
+	struct opal_command_buffer cmd;
+	struct occ_response_buffer rsp;
 } __packed;
 
 static bool occ_reset;
@@ -841,6 +929,326 @@ done:
 	unlock(&occ_lock);
 }
 
+/* OPAL-OCC Command/Response Interface */
+
+enum occ_state {
+	OCC_STATE_NOT_RUNNING		= 0x00,
+	OCC_STATE_STANDBY		= 0x01,
+	OCC_STATE_OBSERVATION		= 0x02,
+	OCC_STATE_ACTIVE		= 0x03,
+	OCC_STATE_SAFE			= 0x04,
+	OCC_STATE_CHARACTERIZATION	= 0x05,
+};
+
+enum occ_role {
+	OCC_ROLE_SLAVE		= 0x0,
+	OCC_ROLE_MASTER		= 0x1,
+};
+
+enum occ_cmd {
+	OCC_CMD_CLEAR_SENSOR_DATA,
+	OCC_CMD_SET_POWER_CAP,
+	OCC_CMD_SET_POWER_SHIFTING_RATIO,
+	OCC_CMD_LAST
+};
+
+struct opal_occ_cmd_info {
+	enum	occ_cmd cmd;
+	u8	cmd_value;
+	u16	cmd_size;
+	u16	rsp_size;
+	int	timeout_ms;
+	u16	state_mask;
+	u8	role_mask;
+};
+
+static struct opal_occ_cmd_info occ_cmds[] = {
+	{	OCC_CMD_CLEAR_SENSOR_DATA,
+		0xD0, 4, 4, 1000,
+		PPC_BIT16(OCC_STATE_OBSERVATION) |
+		PPC_BIT16(OCC_STATE_ACTIVE) |
+		PPC_BIT16(OCC_STATE_CHARACTERIZATION),
+		PPC_BIT8(OCC_ROLE_MASTER) | PPC_BIT8(OCC_ROLE_SLAVE)
+	},
+	{	OCC_CMD_SET_POWER_CAP,
+		0xD1, 2, 2, 1000,
+		PPC_BIT16(OCC_STATE_OBSERVATION) |
+		PPC_BIT16(OCC_STATE_ACTIVE) |
+		PPC_BIT16(OCC_STATE_CHARACTERIZATION),
+		PPC_BIT8(OCC_ROLE_MASTER)
+	},
+	{	OCC_CMD_SET_POWER_SHIFTING_RATIO,
+		0xD2, 1, 1, 1000,
+		PPC_BIT16(OCC_STATE_OBSERVATION) |
+		PPC_BIT16(OCC_STATE_ACTIVE) |
+		PPC_BIT16(OCC_STATE_CHARACTERIZATION),
+		PPC_BIT8(OCC_ROLE_MASTER) | PPC_BIT8(OCC_ROLE_SLAVE)
+	},
+};
+
+enum occ_response_status {
+	OCC_RSP_SUCCESS			= 0x00,
+	OCC_RSP_INVALID_COMMAND		= 0x11,
+	OCC_RSP_INVALID_CMD_DATA_LENGTH	= 0x12,
+	OCC_RSP_INVALID_DATA		= 0x13,
+	OCC_RSP_INTERNAL_ERROR		= 0x15,
+};
+
+#define OCC_FLAG_RSP_READY		0x01
+#define OCC_FLAG_CMD_IN_PROGRESS	0x02
+#define OPAL_FLAG_CMD_READY		0x80
+
+struct opal_occ_cmd_data {
+	u8 *data;
+	enum occ_cmd cmd;
+};
+
+static struct cmd_interface {
+	struct lock queue_lock;
+	struct timer timeout;
+	struct opal_occ_cmd_data *cdata;
+	struct opal_command_buffer *cmd;
+	struct occ_response_buffer *rsp;
+	u8 *occ_state;
+	u8 *valid;
+	u32 chip_id;
+	u32 token;
+	u8 occ_role;
+	u8 request_id;
+	bool cmd_in_progress;
+	bool retry;
+} *chips;
+
+static int nr_occs;
+
+static inline struct cmd_interface *get_chip_cmd_interface(int chip_id)
+{
+	int i;
+
+	for (i = 0; i < nr_occs; i++)
+		if (chips[i].chip_id == chip_id)
+			return &chips[i];
+
+	return NULL;
+}
+
+static inline bool occ_in_progress(struct cmd_interface *chip)
+{
+	return (chip->rsp->flag == OCC_FLAG_CMD_IN_PROGRESS);
+}
+
+static int write_occ_cmd(struct cmd_interface *chip)
+{
+	struct opal_command_buffer *cmd = chip->cmd;
+	enum occ_cmd ocmd = chip->cdata->cmd;
+
+	if (!chip->retry && occ_in_progress(chip)) {
+		chip->cmd_in_progress = false;
+		return OPAL_BUSY;
+	}
+
+	cmd->flag = chip->rsp->flag = 0;
+	cmd->cmd = occ_cmds[ocmd].cmd_value;
+	cmd->request_id = chip->request_id++;
+	cmd->data_size = occ_cmds[ocmd].cmd_size;
+	memcpy(&cmd->data, chip->cdata->data, cmd->data_size);
+	cmd->flag = OPAL_FLAG_CMD_READY;
+
+	schedule_timer(&chip->timeout,
+		       msecs_to_tb(occ_cmds[ocmd].timeout_ms));
+
+	return OPAL_ASYNC_COMPLETION;
+}
+
+static int64_t __unused opal_occ_command(struct cmd_interface *chip, int token,
+					 struct opal_occ_cmd_data *cdata)
+{
+	int rc;
+
+	if (!(*chip->valid) ||
+	    (!(PPC_BIT16(*chip->occ_state) & occ_cmds[cdata->cmd].state_mask)))
+		return OPAL_HARDWARE;
+
+	if (!(PPC_BIT8(chip->occ_role) & occ_cmds[cdata->cmd].role_mask))
+		return OPAL_PERMISSION;
+
+	lock(&chip->queue_lock);
+	if (chip->cmd_in_progress) {
+		rc = OPAL_BUSY;
+		goto out;
+	}
+
+	chip->cdata = cdata;
+	chip->token = token;
+	chip->cmd_in_progress = true;
+	chip->retry = false;
+	rc = write_occ_cmd(chip);
+out:
+	unlock(&chip->queue_lock);
+	return rc;
+}
+
+static inline bool sanity_check_opal_cmd(struct opal_command_buffer *cmd,
+					 struct cmd_interface *chip)
+{
+	return ((cmd->cmd == occ_cmds[chip->cdata->cmd].cmd_value) &&
+		(cmd->request_id == chip->request_id - 1) &&
+		(cmd->data_size == occ_cmds[chip->cdata->cmd].cmd_size));
+}
+
+static inline bool check_occ_rsp(struct opal_command_buffer *cmd,
+				 struct occ_response_buffer *rsp)
+{
+	if (cmd->cmd != rsp->cmd) {
+		prlog(PR_DEBUG, "OCC: Command value mismatch in OCC response"
+		      "rsp->cmd = %d cmd->cmd = %d\n", rsp->cmd, cmd->cmd);
+		return false;
+	}
+
+	if (cmd->request_id != rsp->request_id) {
+		prlog(PR_DEBUG, "OCC: Request ID mismatch in OCC response"
+		      "rsp->request_id = %d cmd->request_id = %d\n",
+		      rsp->request_id, cmd->request_id);
+		return false;
+	}
+
+	return true;
+}
+
+static inline void queue_occ_rsp_msg(int token, int rc)
+{
+	int ret;
+
+	ret = opal_queue_msg(OPAL_MSG_ASYNC_COMP, NULL, NULL, token, rc);
+	if (ret)
+		prerror("OCC: Failed to queue OCC response status message\n");
+}
+
+static void occ_cmd_timeout_handler(struct timer *t __unused, void *data,
+				    uint64_t now __unused)
+{
+	struct cmd_interface *chip = data;
+
+	lock(&chip->queue_lock);
+	if (!chip->cmd_in_progress)
+		goto exit;
+
+	if (!chip->retry) {
+		prlog(PR_DEBUG, "OCC: Command timeout, retrying\n");
+		chip->retry = true;
+		write_occ_cmd(chip);
+	} else {
+		chip->cmd_in_progress = false;
+		queue_occ_rsp_msg(chip->token, OPAL_TIMEOUT);
+		prlog(PR_DEBUG, "OCC: Command timeout after retry\n");
+	}
+exit:
+	unlock(&chip->queue_lock);
+}
+
+static int read_occ_rsp(struct occ_response_buffer *rsp)
+{
+	switch (rsp->status) {
+	case OCC_RSP_SUCCESS:
+		return OPAL_SUCCESS;
+	case OCC_RSP_INVALID_COMMAND:
+		prlog(PR_DEBUG, "OCC: Rsp status: Invalid command\n");
+		break;
+	case OCC_RSP_INVALID_CMD_DATA_LENGTH:
+		prlog(PR_DEBUG, "OCC: Rsp status: Invalid command data length\n");
+		break;
+	case OCC_RSP_INVALID_DATA:
+		prlog(PR_DEBUG, "OCC: Rsp status: Invalid command data\n");
+		break;
+	case OCC_RSP_INTERNAL_ERROR:
+		prlog(PR_DEBUG, "OCC: Rsp status: OCC internal error\n");
+		break;
+	default:
+		break;
+	}
+
+	/* Clear the OCC response flag */
+	rsp->flag = 0;
+	return OPAL_INTERNAL_ERROR;
+}
+
+static void handle_occ_rsp(uint32_t chip_id)
+{
+	struct cmd_interface *chip;
+	struct opal_command_buffer *cmd;
+	struct occ_response_buffer *rsp;
+
+	chip = get_chip_cmd_interface(chip_id);
+	if (!chip)
+		return;
+
+	cmd = chip->cmd;
+	rsp = chip->rsp;
+
+	/*Read rsp*/
+	if (rsp->flag != OCC_FLAG_RSP_READY)
+		return;
+	lock(&chip->queue_lock);
+	if (!chip->cmd_in_progress)
+		goto exit;
+
+	cancel_timer(&chip->timeout);
+	if (!sanity_check_opal_cmd(cmd, chip) ||
+	    !check_occ_rsp(cmd, rsp)) {
+		if (!chip->retry) {
+			prlog(PR_DEBUG, "OCC: Command-response mismatch, retrying\n");
+			chip->retry = true;
+			write_occ_cmd(chip);
+		} else {
+			chip->cmd_in_progress = false;
+			queue_occ_rsp_msg(chip->token, OPAL_INTERNAL_ERROR);
+			prlog(PR_DEBUG, "OCC: Command-response mismatch\n");
+		}
+		goto exit;
+	}
+
+	chip->cmd_in_progress = false;
+	queue_occ_rsp_msg(chip->token, read_occ_rsp(chip->rsp));
+exit:
+	unlock(&chip->queue_lock);
+}
+
+static void occ_cmd_interface_init(void)
+{
+	struct occ_dynamic_data *data;
+	struct occ_pstate_table *pdata;
+	struct proc_chip *chip;
+	int i = 0;
+
+	chip = next_chip(NULL);
+	pdata = get_occ_pstate_table(chip);
+	if (pdata->version != 0x90)
+		return;
+
+	for_each_chip(chip)
+		nr_occs++;
+
+	chips = malloc(sizeof(*chips) * nr_occs);
+	assert(chips);
+
+	for_each_chip(chip) {
+		pdata = get_occ_pstate_table(chip);
+		data = get_occ_dynamic_data(chip);
+		chips[i].chip_id = chip->id;
+		chips[i].occ_role = pdata->v9.occ_role;
+		chips[i].occ_state = &data->occ_state;
+		chips[i].valid = &pdata->valid;
+		chips[i].cmd = &data->cmd;
+		chips[i].rsp = &data->rsp;
+		init_lock(&chips[i].queue_lock);
+		chips[i].cmd_in_progress = false;
+		chips[i].request_id = 0;
+		init_timer(&chips[i].timeout, occ_cmd_timeout_handler,
+			   &chips[i]);
+		i++;
+	}
+}
+
 /* CPU-OCC PState init */
 /* Called after OCC init on P8 and P9 */
 void occ_pstates_init(void)
@@ -908,6 +1316,9 @@ void occ_pstates_init(void)
 		chip->throttle = 0;
 	opal_add_poller(occ_throttle_poll, NULL);
 	occ_pstates_initialized = true;
+
+	/* Init OPAL-OCC command-response interface */
+	occ_cmd_interface_init();
 }
 
 struct occ_load_req {
@@ -1407,8 +1818,10 @@ void occ_p9_interrupt(uint32_t chip_id)
 	if (ireg & OCB_OCI_OCIMISC_IRQ_TMGT)
 		prd_tmgt_interrupt(chip_id);
 
-	if (ireg & OCB_OCI_OCIMISC_IRQ_SHMEM)
+	if (ireg & OCB_OCI_OCIMISC_IRQ_SHMEM) {
 		occ_throttle_poll(NULL);
+		handle_occ_rsp(chip_id);
+	}
 
 	if (ireg & OCB_OCI_OCIMISC_IRQ_I2C)
 		p9_i2c_bus_owner_change(chip_id);
@@ -1433,5 +1846,3 @@ void occ_fsp_init(void)
 	if (fsp_present())
 		fsp_register_client(&fsp_occ_client, FSP_MCLASS_OCC);
 }
-
-
diff --git a/include/opal-api.h b/include/opal-api.h
index 2a8816a..d2137d6 100644
--- a/include/opal-api.h
+++ b/include/opal-api.h
@@ -55,6 +55,7 @@
 #define OPAL_XSCOM_CTR_OFFLINED	-30
 #define OPAL_XIVE_PROVISIONING	-31
 #define OPAL_XIVE_FREE_ACTIVE	-32
+#define OPAL_TIMEOUT		-33
 
 /* API Tokens (in r0) */
 #define OPAL_INVALID_CALL		       -1