Re: [PATCH 3/5] hwmon: (socfpga) Add hardware monitoring support on SoCFPGA platforms

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On 4/10/2023 9:44 PM, Guenter Roeck wrote:
On 4/10/23 08:33, dinh.nguyen@xxxxxxxxxxxxxxx wrote:
From: Dinh Nguyen <dinh.nguyen@xxxxxxxxxxxxxxx>

The driver supports 64-bit SoCFPGA platforms for temperature and voltage
reading using the platform's SDM(Secure Device Manager). The driver
also uses the Stratix10 Service layer driver.

This driver only supports OF SoCFPGA 64-bit platforms.

Reviewed-by: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Signed-off-by: Dinh Nguyen <dinh.nguyen@xxxxxxxxxxxxxxx>
---
  Documentation/hwmon/index.rst                 |   1 +
  Documentation/hwmon/socfpga-hwmon.rst         |  30 ++
  drivers/firmware/stratix10-svc.c              |  18 +-

Changes outside the hwmon subsystem need to be in a separate patch.

will separate...


drivers/hwmon/Kconfig                         |  11 +
  drivers/hwmon/Makefile                        |   1 +
  drivers/hwmon/socfpga-hwmon.c                 | 406 ++++++++++++++++++
  include/linux/firmware/intel/stratix10-smc.h  |  34 ++
  .../firmware/intel/stratix10-svc-client.h     |   6 +
  8 files changed, 506 insertions(+), 1 deletion(-)
  create mode 100644 Documentation/hwmon/socfpga-hwmon.rst
  create mode 100644 drivers/hwmon/socfpga-hwmon.c


...
+
+enum hwmon_type_op {
+    SOCFPGA_HWMON_TYPE_TEMP,
+    SOCFPGA_HWMON_TYPE_VOLT,
+    SOCFPGA_HWMON_TYPE_MAX

Unused define

Removed.


+};
+
+static const char *const hwmon_types_str[] = { "temperature", "voltage" };
+
+static umode_t socfpga_is_visible(const void *dev,
+                  enum hwmon_sensor_types type,
+                  u32 attr, int chan)
+{
+    switch (type) {
+    case hwmon_temp:
+    case hwmon_in:
+        return 0444;
+    default:
+        return 0;
+    }
+}
+
+static void socfpga_smc_callback(struct stratix10_svc_client *client,
+                      struct stratix10_svc_cb_data *data)
+{
+    struct socfpga_hwmon_priv *priv = client->priv;
+    struct arm_smccc_res *res = data->kaddr1;
+
+    if (data->status == BIT(SVC_STATUS_OK))    {
+        if (priv->msg.command == COMMAND_HWMON_READTEMP)
+            priv->temperature.value = res->a0;
+        else
+            priv->voltage.value = res->a0;
+    } else
+        dev_err(client->dev, "%s returned 0x%lX\n", __func__, res->a0);
+

Missing { } in else branch. Please run checkpatch --strict and fix
continuation line alignment issues as well as unbalanced if/else
reports.
Will do.

+    complete(&priv->completion);
+}
+
+static int socfpga_hwmon_send(struct socfpga_hwmon_priv *priv)
+{
+    int ret;
+
+    priv->client.receive_cb = socfpga_smc_callback;
+
+    ret = stratix10_svc_send(priv->chan, &priv->msg);
+    if (ret < 0)
+        return ret;
+
+    if (!wait_for_completion_timeout(&priv->completion, HWMON_TIMEOUT)) {
+        dev_err(priv->client.dev, "SMC call timeout!\n");
+        return -ETIMEDOUT;
+    }
+
+    return 0;
+}
+
+static int socfpga_hwmon_err_to_errno(struct socfpga_hwmon_priv *priv)
+{
+    int value = priv->temperature.value;
+
+    if (!(value & ETEMP_ERROR))
+        return 0;
+

This is odd. int is normally 32 bit, this function is called from
socfpga_read() for temperatures, which presumably are defined
as "signed 32-bit fixed point binary". That means that negative
temperatures would be treated as errors. Please verify.

That's correct, if bit 31 is set, then it indicates an error.


+    dev_err(priv->client.dev, "temperature sensor code 0x%08x\n", value);
+

Please don't clog the log with such messages.

Removed.


+    value &= ~ETEMP_ERROR;
+    switch (value) {
+    case ETEMP_NOT_PRESENT:
+        return -ENOENT;
+    case ETEMP_CORRUPT:
+    case ETEMP_NOT_INITIALIZED:
+        return -ENODATA;
+    case ETEMP_BUSY:
+        return -EBUSY;
+    case ETEMP_INACTIVE:
+    case ETEMP_TIMEOUT:
+    case ETEMP_TOO_OLD:
+        return -EAGAIN;
+    default:
+        /* Unknown error */
+        return -EINVAL;

Should be -EIO.

Replaced.
+    }
+}
+
+static int socfpga_read(struct device *dev, enum hwmon_sensor_types type,
+            u32 attr, int chan, long *val)
+{
+    struct socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+    int ret;
+
+    mutex_lock(&priv->lock);
+    reinit_completion(&priv->completion);
+
+    switch (type) {
+    case hwmon_temp:
+        priv->msg.arg[0] = BIT_ULL(priv->temperature.chan[chan]);
+        priv->msg.command = COMMAND_HWMON_READTEMP;
+        if (socfpga_hwmon_send(priv))
+            goto status_done;
+
+        ret = socfpga_hwmon_err_to_errno(priv);
+        if (ret)
+            break;
+        /*
+         * The Temperature Sensor IP core returns the Celsius
+         * temperature value in signed 32-bit fixed point binary
+         * format, with eight bits below binary point.
+         */
+        *val = (priv->temperature.value * MILLIDEGREE_PER_DEGREE) / 256;
+        break;
+    case hwmon_in: /* Read voltage */

Pointless comment

Removed.


+        priv->msg.arg[0] = BIT_ULL(priv->voltage.chan[chan]);
+        priv->msg.command = COMMAND_HWMON_READVOLT;
+        if (socfpga_hwmon_send(priv))
+            goto status_done;
+

No error check for voltage sensors ?
Also, unless I am missing something, the error bailout leaves ret
undefined.

There are no error readings for the voltage sensors specified in the spec. Will update

the ret value.

+        /*
+         * The Voltage Sensor IP core returns the sampled voltage
+         * in unsigned 32-bit fixed point binary format, with 16 bits
+         * below binary point.
+         */
+        *val = (priv->voltage.value * MILLIVOLT_PER_VOLT) / 65536;
+        break;
+    default:
+        ret = -EOPNOTSUPP;
+        break;
+    }
+
+status_done:
+    stratix10_svc_done(priv->chan);
+    mutex_unlock(&priv->lock);
+    return ret;
+}
+
+static int socfpga_read_string(struct device *dev,
+                   enum hwmon_sensor_types type, u32 attr,
+                   int chan, const char **str)
+{
+    struct socfpga_hwmon_priv *priv = dev_get_drvdata(dev);
+
+    switch (type) {
+    case hwmon_in:
+        *str = priv->voltage.names[chan];
+        return 0;
+    case hwmon_temp:
+        *str = priv->temperature.names[chan];
+        return 0;
+    default:
+        return -EOPNOTSUPP;
+    }
+}
+
+static const struct hwmon_ops socfpga_ops = {
+    .is_visible = socfpga_is_visible,
+    .read = socfpga_read,
+    .read_string = socfpga_read_string,
+};
+
+static const struct hwmon_channel_info *socfpga_info[] = {
+    HWMON_CHANNEL_INFO(temp,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL,
+        HWMON_T_INPUT | HWMON_T_LABEL, HWMON_T_INPUT | HWMON_T_LABEL),
+    HWMON_CHANNEL_INFO(in,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL,
+        HWMON_I_INPUT | HWMON_I_LABEL, HWMON_I_INPUT | HWMON_I_LABEL),
+    NULL
+};
+
+static const struct hwmon_chip_info socfpga_chip_info = {
+    .ops = &socfpga_ops,
+    .info = socfpga_info,
+};
+
+static int socfpga_add_channel(struct device *dev,  const char *type,
+                u32 val, const char *label,
+                struct socfpga_hwmon_priv *priv)
+{
+    int type_index;
+    struct socfpga_hwmon_chan *p;
+
+    type_index = match_string(hwmon_types_str, ARRAY_SIZE(hwmon_types_str), type);
+    switch (type_index) {
+    case SOCFPGA_HWMON_TYPE_TEMP:
+        p = &priv->temperature;
+        break;
+    case SOCFPGA_HWMON_TYPE_VOLT:
+        p = &priv->voltage;
+        break;
+    default:
+        return -ENODATA;
+    }
+    if (p->n >= SOCFPGA_HWMON_MAXSENSORS)
+        return -ENOSPC;
+
+    p->names[p->n] = label;
+    p->chan[p->n] = val;
+    p->n++;
+
+    return 0;
+}
+
+static int socfpga_probe_child_from_dt(struct device *dev,
+                       struct device_node *child,
+                       struct socfpga_hwmon_priv *priv)
+{
+    struct device_node *grandchild;
+    const char *label;
+    const char *type;
+    u32 val;
+    int ret;
+
+    if (of_property_read_string(child, "name", &type))
+        return dev_err_probe(dev, -EINVAL, "No type for %pOF\n", child);
+
+    for_each_child_of_node(child, grandchild) {
+        ret = of_property_read_u32(grandchild, "reg", &val);
+        if (ret)
+            return dev_err_probe(dev, ret, "missing reg property of %pOF\n",
+                         grandchild);
+
+        ret = of_property_read_string(grandchild, "label", &label);
+        if (ret)
+            return dev_err_probe(dev, ret, "missing label propoerty of %pOF\n",
+                         grandchild);
+        ret = socfpga_add_channel(dev, type, val, label, priv);
+        if (ret == -ENOSPC)
+            return dev_err_probe(dev, ret, "too many channels, only %d supported\n",
+                         SOCFPGA_HWMON_MAXSENSORS);
+    }
+    return 0;
+}
+
+static int socfpga_probe_from_dt(struct device *dev,
+                 struct socfpga_hwmon_priv *priv)
+{
+    const struct device_node *np = dev->of_node;
+    struct device_node *child;
+    int ret = 0;
+
+    for_each_child_of_node(np, child) {
+        ret = socfpga_probe_child_from_dt(dev, child, priv);
+        if (ret)
+            break;
+    }
+    of_node_put(child);
+
+    return ret;
+}
+
+static int socfpga_hwmon_probe(struct platform_device *pdev)
+{
+    struct device *dev = &pdev->dev;
+    struct device *hwmon_dev;
+    struct socfpga_hwmon_priv *priv;
+    int ret;
+
+    priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
+    if (!priv)
+        return -ENOMEM;
+
+    priv->client.dev = dev;
+    priv->client.priv = priv;
+
+    ret = socfpga_probe_from_dt(dev, priv);
+    if (ret)
+        return dev_err_probe(dev, ret, "Unable to probe from device tree\n");
+
+    mutex_init(&priv->lock);
+    init_completion(&priv->completion);
+    hwmon_dev = devm_hwmon_device_register_with_info(dev, "socfpgahwmon",
+                             priv,
+                             &socfpga_chip_info,
+                             NULL);
+    if (IS_ERR(hwmon_dev))
+        return PTR_ERR(hwmon_dev);
+
+    priv->chan = stratix10_svc_request_channel_byname(&priv->client,
+                    SVC_CLIENT_HWMON);

This is racy: hwmon attributes exist here, and priv->chan may be accessed before
it is set.

Fixed in v2.


+    if (IS_ERR(priv->chan))
+        return dev_err_probe(dev, PTR_ERR(priv->chan),
+                     "couldn't get service channel %s\n",
+                     SVC_CLIENT_RSU);
+
+    platform_set_drvdata(pdev, priv);
+
+    return 0;
+}
+
+static int socfpga_hwmon_remove(struct platform_device *pdev)
+{
+    struct socfpga_hwmon_priv *priv = platform_get_drvdata(pdev);
+
+    stratix10_svc_free_channel(priv->chan);

This releases the channel before the hwmon device is released.
Another race condition.

fixed in V2.

Thanks for the review!

Dinh




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