bus: mhi: core: Improvements to the channel handling state machine

Improve the channel handling state machine such that all commands
go through a common function and a validation process to ensure
that the state machine is not violated in any way and adheres to
the MHI specification. Using this common function allows MHI to
eliminate some unnecessary debug messages and code duplication.

Signed-off-by: Bhaumik Bhatt <bbhatt@codeaurora.org>
Reviewed-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Link: https://lore.kernel.org/r/1617311778-1254-4-git-send-email-bbhatt@codeaurora.org
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>

diff --git a/drivers/bus/mhi/core/init.c b/drivers/bus/mhi/core/init.c
index a507895f6209ee7172a28e3701906c605d2f848c..0e54384e9fc57971facfdae9a45cdd49f13fd8e4 100644 (file)
--- a/drivers/bus/mhi/core/init.c
+++ b/drivers/bus/mhi/core/init.c
@@ -56,6 +56,12 @@ const char * const mhi_state_str[MHI_STATE_MAX] = {
        [MHI_STATE_SYS_ERR] = "SYS ERROR",
 };
 
+const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX] = {
+       [MHI_CH_STATE_TYPE_RESET] = "RESET",
+       [MHI_CH_STATE_TYPE_STOP] = "STOP",
+       [MHI_CH_STATE_TYPE_START] = "START",
+};
+
 static const char * const mhi_pm_state_str[] = {
        [MHI_PM_STATE_DISABLE] = "DISABLE",
        [MHI_PM_STATE_POR] = "POWER ON RESET",

diff --git a/drivers/bus/mhi/core/internal.h b/drivers/bus/mhi/core/internal.h
index e690f154212fb3764ba1252a7df499b5674f25b7..5b9ea66b92dc32fb7dce14f4a4db5ea7419839af 100644 (file)
--- a/drivers/bus/mhi/core/internal.h
+++ b/drivers/bus/mhi/core/internal.h
@@ -369,6 +369,18 @@ enum mhi_ch_state {
        MHI_CH_STATE_ERROR = 0x5,
 };
 
+enum mhi_ch_state_type {
+       MHI_CH_STATE_TYPE_RESET,
+       MHI_CH_STATE_TYPE_STOP,
+       MHI_CH_STATE_TYPE_START,
+       MHI_CH_STATE_TYPE_MAX,
+};
+
+extern const char * const mhi_ch_state_type_str[MHI_CH_STATE_TYPE_MAX];
+#define TO_CH_STATE_TYPE_STR(state) (((state) >= MHI_CH_STATE_TYPE_MAX) ? \
+                                    "INVALID_STATE" : \
+                                    mhi_ch_state_type_str[(state)])
+
 #define MHI_INVALID_BRSTMODE(mode) (mode != MHI_DB_BRST_DISABLE && \
                                    mode != MHI_DB_BRST_ENABLE)
 

diff --git a/drivers/bus/mhi/core/main.c b/drivers/bus/mhi/core/main.c
index 4a7d3c7ec5540edcebea54d87ab4729b88592808..16bf8ec4e289139a3ab59e8fd73c4c31daf046df 100644 (file)
--- a/drivers/bus/mhi/core/main.c
+++ b/drivers/bus/mhi/core/main.c
@@ -1242,56 +1242,105 @@ int mhi_send_cmd(struct mhi_controller *mhi_cntrl,
        return 0;
 }
 
-static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
-                                   struct mhi_chan *mhi_chan)
+static int mhi_update_channel_state(struct mhi_controller *mhi_cntrl,
+                                   struct mhi_chan *mhi_chan,
+                                   enum mhi_ch_state_type to_state)
 {
-       int ret;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
+       enum mhi_cmd_type cmd = MHI_CMD_NOP;
+       int ret;
 
-       dev_dbg(dev, "Entered: unprepare channel:%d\n", mhi_chan->chan);
-
-       /* no more processing events for this channel */
-       mutex_lock(&mhi_chan->mutex);
-       write_lock_irq(&mhi_chan->lock);
-       if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
-           mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
+       dev_dbg(dev, "%d: Updating channel state to: %s\n", mhi_chan->chan,
+               TO_CH_STATE_TYPE_STR(to_state));
+
+       switch (to_state) {
+       case MHI_CH_STATE_TYPE_RESET:
+               write_lock_irq(&mhi_chan->lock);
+               if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
+                   mhi_chan->ch_state != MHI_CH_STATE_ENABLED &&
+                   mhi_chan->ch_state != MHI_CH_STATE_SUSPENDED) {
+                       write_unlock_irq(&mhi_chan->lock);
+                       return -EINVAL;
+               }
+               mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
                write_unlock_irq(&mhi_chan->lock);
-               mutex_unlock(&mhi_chan->mutex);
-               return;
-       }
 
-       mhi_chan->ch_state = MHI_CH_STATE_DISABLED;
-       write_unlock_irq(&mhi_chan->lock);
+               cmd = MHI_CMD_RESET_CHAN;
+               break;
+       case MHI_CH_STATE_TYPE_STOP:
+               if (mhi_chan->ch_state != MHI_CH_STATE_ENABLED)
+                       return -EINVAL;
 
-       reinit_completion(&mhi_chan->completion);
-       read_lock_bh(&mhi_cntrl->pm_lock);
-       if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
-               read_unlock_bh(&mhi_cntrl->pm_lock);
-               goto error_invalid_state;
+               cmd = MHI_CMD_STOP_CHAN;
+               break;
+       case MHI_CH_STATE_TYPE_START:
+               if (mhi_chan->ch_state != MHI_CH_STATE_STOP &&
+                   mhi_chan->ch_state != MHI_CH_STATE_DISABLED)
+                       return -EINVAL;
+
+               cmd = MHI_CMD_START_CHAN;
+               break;
+       default:
+               dev_err(dev, "%d: Channel state update to %s not allowed\n",
+                       mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+               return -EINVAL;
        }
 
        mhi_cntrl->wake_toggle(mhi_cntrl);
-       read_unlock_bh(&mhi_cntrl->pm_lock);
-
        mhi_cntrl->runtime_get(mhi_cntrl);
        mhi_cntrl->runtime_put(mhi_cntrl);
-       ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_RESET_CHAN);
-       if (ret)
-               goto error_invalid_state;
 
-       /* even if it fails we will still reset */
+       reinit_completion(&mhi_chan->completion);
+       ret = mhi_send_cmd(mhi_cntrl, mhi_chan, cmd);
+       if (ret) {
+               dev_err(dev, "%d: Failed to send %s channel command\n",
+                       mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+               return ret;
+       }
+
        ret = wait_for_completion_timeout(&mhi_chan->completion,
-                               msecs_to_jiffies(mhi_cntrl->timeout_ms));
-       if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS)
+                                      msecs_to_jiffies(mhi_cntrl->timeout_ms));
+       if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
                dev_err(dev,
-                       "Failed to receive cmd completion, still resetting\n");
+                       "%d: Failed to receive %s channel command completion\n",
+                       mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+               return -EIO;
+       }
+
+       if (to_state != MHI_CH_STATE_TYPE_RESET) {
+               write_lock_irq(&mhi_chan->lock);
+               mhi_chan->ch_state = (to_state == MHI_CH_STATE_TYPE_START) ?
+                                     MHI_CH_STATE_ENABLED : MHI_CH_STATE_STOP;
+               write_unlock_irq(&mhi_chan->lock);
+       }
+
+       dev_dbg(dev, "%d: Channel state change to %s successful\n",
+               mhi_chan->chan, TO_CH_STATE_TYPE_STR(to_state));
+
+       return 0;
+}
+
+static void __mhi_unprepare_channel(struct mhi_controller *mhi_cntrl,
+                                   struct mhi_chan *mhi_chan)
+{
+       int ret;
+       struct device *dev = &mhi_cntrl->mhi_dev->dev;
+
+       mutex_lock(&mhi_chan->mutex);
+
+       /* no more processing events for this channel */
+       ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
+                                      MHI_CH_STATE_TYPE_RESET);
+       if (ret)
+               dev_err(dev, "%d: Failed to reset channel, still resetting\n",
+                       mhi_chan->chan);
 
-error_invalid_state:
        if (!mhi_chan->offload_ch) {
                mhi_reset_chan(mhi_cntrl, mhi_chan);
                mhi_deinit_chan_ctxt(mhi_cntrl, mhi_chan);
        }
-       dev_dbg(dev, "chan:%d successfully resetted\n", mhi_chan->chan);
+       dev_dbg(dev, "%d: successfully reset\n", mhi_chan->chan);
+
        mutex_unlock(&mhi_chan->mutex);
 }
 
@@ -1301,8 +1350,6 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
        int ret = 0;
        struct device *dev = &mhi_cntrl->mhi_dev->dev;
 
-       dev_dbg(dev, "Preparing channel: %d\n", mhi_chan->chan);
-
        if (!(BIT(mhi_cntrl->ee) & mhi_chan->ee_mask)) {
                dev_err(dev,
                        "Current EE: %s Required EE Mask: 0x%x for chan: %s\n",
@@ -1313,14 +1360,6 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 
        mutex_lock(&mhi_chan->mutex);
 
-       /* If channel is not in disable state, do not allow it to start */
-       if (mhi_chan->ch_state != MHI_CH_STATE_DISABLED) {
-               ret = -EIO;
-               dev_dbg(dev, "channel: %d is not in disabled state\n",
-                       mhi_chan->chan);
-               goto error_init_chan;
-       }
-
        /* Check of client manages channel context for offload channels */
        if (!mhi_chan->offload_ch) {
                ret = mhi_init_chan_ctxt(mhi_cntrl, mhi_chan);
@@ -1328,34 +1367,11 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
                        goto error_init_chan;
        }
 
-       reinit_completion(&mhi_chan->completion);
-       read_lock_bh(&mhi_cntrl->pm_lock);
-       if (MHI_PM_IN_ERROR_STATE(mhi_cntrl->pm_state)) {
-               read_unlock_bh(&mhi_cntrl->pm_lock);
-               ret = -EIO;
-               goto error_pm_state;
-       }
-
-       mhi_cntrl->wake_toggle(mhi_cntrl);
-       read_unlock_bh(&mhi_cntrl->pm_lock);
-       mhi_cntrl->runtime_get(mhi_cntrl);
-       mhi_cntrl->runtime_put(mhi_cntrl);
-
-       ret = mhi_send_cmd(mhi_cntrl, mhi_chan, MHI_CMD_START_CHAN);
+       ret = mhi_update_channel_state(mhi_cntrl, mhi_chan,
+                                      MHI_CH_STATE_TYPE_START);
        if (ret)
                goto error_pm_state;
 
-       ret = wait_for_completion_timeout(&mhi_chan->completion,
-                               msecs_to_jiffies(mhi_cntrl->timeout_ms));
-       if (!ret || mhi_chan->ccs != MHI_EV_CC_SUCCESS) {
-               ret = -EIO;
-               goto error_pm_state;
-       }
-
-       write_lock_irq(&mhi_chan->lock);
-       mhi_chan->ch_state = MHI_CH_STATE_ENABLED;
-       write_unlock_irq(&mhi_chan->lock);
-
        /* Pre-allocate buffer for xfer ring */
        if (mhi_chan->pre_alloc) {
                int nr_el = get_nr_avail_ring_elements(mhi_cntrl,
@@ -1393,9 +1409,6 @@ int mhi_prepare_channel(struct mhi_controller *mhi_cntrl,
 
        mutex_unlock(&mhi_chan->mutex);
 
-       dev_dbg(dev, "Chan: %d successfully moved to start state\n",
-               mhi_chan->chan);
-
        return 0;
 
 error_pm_state: