--- /dev/null
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * MIPI SyS-T framing protocol for STM devices.
+ * Copyright (c) 2018, Intel Corporation.
+ */
+
+#include <linux/configfs.h>
+#include <linux/module.h>
+#include <linux/device.h>
+#include <linux/slab.h>
+#include <linux/uuid.h>
+#include <linux/stm.h>
+#include "stm.h"
+
+enum sys_t_message_type {
+ MIPI_SYST_TYPE_BUILD = 0,
+ MIPI_SYST_TYPE_SHORT32,
+ MIPI_SYST_TYPE_STRING,
+ MIPI_SYST_TYPE_CATALOG,
+ MIPI_SYST_TYPE_RAW = 6,
+ MIPI_SYST_TYPE_SHORT64,
+ MIPI_SYST_TYPE_CLOCK,
+};
+
+enum sys_t_message_severity {
+ MIPI_SYST_SEVERITY_MAX = 0,
+ MIPI_SYST_SEVERITY_FATAL,
+ MIPI_SYST_SEVERITY_ERROR,
+ MIPI_SYST_SEVERITY_WARNING,
+ MIPI_SYST_SEVERITY_INFO,
+ MIPI_SYST_SEVERITY_USER1,
+ MIPI_SYST_SEVERITY_USER2,
+ MIPI_SYST_SEVERITY_DEBUG,
+};
+
+enum sys_t_message_build_subtype {
+ MIPI_SYST_BUILD_ID_COMPACT32 = 0,
+ MIPI_SYST_BUILD_ID_COMPACT64,
+ MIPI_SYST_BUILD_ID_LONG,
+};
+
+enum sys_t_message_clock_subtype {
+ MIPI_SYST_CLOCK_TRANSPORT_SYNC = 1,
+};
+
+enum sys_t_message_string_subtype {
+ MIPI_SYST_STRING_GENERIC = 1,
+ MIPI_SYST_STRING_FUNCTIONENTER,
+ MIPI_SYST_STRING_FUNCTIONEXIT,
+ MIPI_SYST_STRING_INVALIDPARAM = 5,
+ MIPI_SYST_STRING_ASSERT = 7,
+ MIPI_SYST_STRING_PRINTF_32 = 11,
+ MIPI_SYST_STRING_PRINTF_64 = 12,
+};
+
+#define MIPI_SYST_TYPE(t) ((u32)(MIPI_SYST_TYPE_ ## t))
+#define MIPI_SYST_SEVERITY(s) ((u32)(MIPI_SYST_SEVERITY_ ## s) << 4)
+#define MIPI_SYST_OPT_LOC BIT(8)
+#define MIPI_SYST_OPT_LEN BIT(9)
+#define MIPI_SYST_OPT_CHK BIT(10)
+#define MIPI_SYST_OPT_TS BIT(11)
+#define MIPI_SYST_UNIT(u) ((u32)(u) << 12)
+#define MIPI_SYST_ORIGIN(o) ((u32)(o) << 16)
+#define MIPI_SYST_OPT_GUID BIT(23)
+#define MIPI_SYST_SUBTYPE(s) ((u32)(MIPI_SYST_ ## s) << 24)
+#define MIPI_SYST_UNITLARGE(u) (MIPI_SYST_UNIT(u & 0xf) | \
+ MIPI_SYST_ORIGIN(u >> 4))
+#define MIPI_SYST_TYPES(t, s) (MIPI_SYST_TYPE(t) | \
+ MIPI_SYST_SUBTYPE(t ## _ ## s))
+
+#define DATA_HEADER (MIPI_SYST_TYPES(STRING, GENERIC) | \
+ MIPI_SYST_SEVERITY(INFO) | \
+ MIPI_SYST_OPT_GUID)
+
+struct sys_t_policy_node {
+ uuid_t uuid;
+ bool do_len;
+ unsigned long ts_interval;
+};
+
+struct sys_t_output {
+ struct sys_t_policy_node node;
+ unsigned long ts_jiffies;
+};
+
+static void sys_t_policy_node_init(void *priv)
+{
+ struct sys_t_policy_node *pn = priv;
+
+ generate_random_uuid(pn->uuid.b);
+}
+
+static int sys_t_output_open(void *priv, struct stm_output *output)
+{
+ struct sys_t_policy_node *pn = priv;
+ struct sys_t_output *opriv;
+
+ opriv = kzalloc(sizeof(*opriv), GFP_ATOMIC);
+ if (!opriv)
+ return -ENOMEM;
+
+ memcpy(&opriv->node, pn, sizeof(opriv->node));
+ output->pdrv_private = opriv;
+
+ return 0;
+}
+
+static void sys_t_output_close(struct stm_output *output)
+{
+ kfree(output->pdrv_private);
+}
+
+static ssize_t sys_t_policy_uuid_show(struct config_item *item,
+ char *page)
+{
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+
+ return sprintf(page, "%pU\n", &pn->uuid);
+}
+
+static ssize_t
+sys_t_policy_uuid_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+ int ret;
+
+ mutex_lock(mutexp);
+ ret = uuid_parse(page, &pn->uuid);
+ mutex_unlock(mutexp);
+
+ return ret < 0 ? ret : count;
+}
+
+CONFIGFS_ATTR(sys_t_policy_, uuid);
+
+static ssize_t sys_t_policy_do_len_show(struct config_item *item,
+ char *page)
+{
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+
+ return sprintf(page, "%d\n", pn->do_len);
+}
+
+static ssize_t
+sys_t_policy_do_len_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+ int ret;
+
+ mutex_lock(mutexp);
+ ret = kstrtobool(page, &pn->do_len);
+ mutex_unlock(mutexp);
+
+ return ret ? ret : count;
+}
+
+CONFIGFS_ATTR(sys_t_policy_, do_len);
+
+static ssize_t sys_t_policy_ts_interval_show(struct config_item *item,
+ char *page)
+{
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+
+ return sprintf(page, "%u\n", jiffies_to_msecs(pn->ts_interval));
+}
+
+static ssize_t
+sys_t_policy_ts_interval_store(struct config_item *item, const char *page,
+ size_t count)
+{
+ struct mutex *mutexp = &item->ci_group->cg_subsys->su_mutex;
+ struct sys_t_policy_node *pn = to_pdrv_policy_node(item);
+ unsigned int ms;
+ int ret;
+
+ mutex_lock(mutexp);
+ ret = kstrtouint(page, 10, &ms);
+ mutex_unlock(mutexp);
+
+ if (!ret) {
+ pn->ts_interval = msecs_to_jiffies(ms);
+ return count;
+ }
+
+ return ret;
+}
+
+CONFIGFS_ATTR(sys_t_policy_, ts_interval);
+
+static struct configfs_attribute *sys_t_policy_attrs[] = {
+ &sys_t_policy_attr_uuid,
+ &sys_t_policy_attr_do_len,
+ &sys_t_policy_attr_ts_interval,
+ NULL,
+};
+
+static inline bool sys_t_need_ts(struct sys_t_output *op)
+{
+ if (op->node.ts_interval &&
+ time_after(op->ts_jiffies + op->node.ts_interval, jiffies)) {
+ op->ts_jiffies = jiffies;
+
+ return true;
+ }
+
+ return false;
+}
+
+static ssize_t sys_t_write(struct stm_data *data, struct stm_output *output,
+ unsigned int chan, const char *buf, size_t count)
+{
+ struct sys_t_output *op = output->pdrv_private;
+ unsigned int c = output->channel + chan;
+ unsigned int m = output->master;
+ const unsigned char nil = 0;
+ u32 header = DATA_HEADER;
+ ssize_t sz;
+
+ /* We require an existing policy node to proceed */
+ if (!op)
+ return -EINVAL;
+
+ if (op->node.do_len)
+ header |= MIPI_SYST_OPT_LEN;
+ if (sys_t_need_ts(op))
+ header |= MIPI_SYST_OPT_TS;
+
+ /*
+ * STP framing rules for SyS-T frames:
+ * * the first packet of the SyS-T frame is timestamped;
+ * * the last packet is a FLAG.
+ */
+ /* Message layout: HEADER / GUID / [LENGTH /][TIMESTAMP /] DATA */
+ /* HEADER */
+ sz = data->packet(data, m, c, STP_PACKET_DATA, STP_PACKET_TIMESTAMPED,
+ 4, (u8 *)&header);
+ if (sz <= 0)
+ return sz;
+
+ /* GUID */
+ sz = stm_data_write(data, m, c, false, op->node.uuid.b, UUID_SIZE);
+ if (sz <= 0)
+ return sz;
+
+ /* [LENGTH] */
+ if (op->node.do_len) {
+ u16 length = count;
+
+ sz = data->packet(data, m, c, STP_PACKET_DATA, 0, 2,
+ (u8 *)&length);
+ if (sz <= 0)
+ return sz;
+ }
+
+ /* [TIMESTAMP] */
+ if (header & MIPI_SYST_OPT_TS) {
+ u64 ts = ktime_get_real_ns();
+
+ sz = stm_data_write(data, m, c, false, &ts, sizeof(ts));
+ if (sz <= 0)
+ return sz;
+ }
+
+ /* DATA */
+ sz = stm_data_write(data, m, c, false, buf, count);
+ if (sz > 0)
+ data->packet(data, m, c, STP_PACKET_FLAG, 0, 0, &nil);
+
+ return sz;
+}
+
+static const struct stm_protocol_driver sys_t_pdrv = {
+ .owner = THIS_MODULE,
+ .name = "p_sys-t",
+ .priv_sz = sizeof(struct sys_t_policy_node),
+ .write = sys_t_write,
+ .policy_attr = sys_t_policy_attrs,
+ .policy_node_init = sys_t_policy_node_init,
+ .output_open = sys_t_output_open,
+ .output_close = sys_t_output_close,
+};
+
+static int sys_t_stm_init(void)
+{
+ return stm_register_protocol(&sys_t_pdrv);
+}
+
+static void sys_t_stm_exit(void)
+{
+ stm_unregister_protocol(&sys_t_pdrv);
+}
+
+module_init(sys_t_stm_init);
+module_exit(sys_t_stm_exit);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("MIPI SyS-T STM framing protocol driver");
+MODULE_AUTHOR("Alexander Shishkin <alexander.shishkin@linux.intel.com>");
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