From: Morten Borup Petersen <morten.petersen@xxxxxxx>
When in multi-word mode, the mailbox controller will provide a single
mailbox. It is required that the MHU device has at least 2 channel windows
available for the MHU to function in multi-word mode.
Transmitting and receiving data through the mailbox framework in
multi-word mode is done through a struct arm_mbox_msg.
Signed-off-by: Morten Borup Petersen <morten.petersen@xxxxxxx>
Signed-off-by: Tushar Khandelwal <tushar.khandelwal@xxxxxxx>
Cc: jassisinghbrar@xxxxxxxxx
Cc: devicetree@xxxxxxxxxxxxxxx
---
drivers/mailbox/arm_mhu_v2.c | 225 +++++++++++++++++++++++++++++++++++
1 file changed, 225 insertions(+)
diff --git a/drivers/mailbox/arm_mhu_v2.c b/drivers/mailbox/arm_mhu_v2.c
index 0e3fa5917925..324b19bdb28a 100644
--- a/drivers/mailbox/arm_mhu_v2.c
+++ b/drivers/mailbox/arm_mhu_v2.c
@@ -430,6 +430,228 @@ static const struct mhuv2_ops mhuv2_single_word_ops = {
};
/* ========================================================================== */
+/* ================ Multi word transport protocol operations ================ */
+static inline int mhuv2_read_data_multi_word(struct arm_mhuv2 *mhuv2,
+ struct mbox_chan *chan,
+ struct arm_mbox_msg *msg)
+{
+ int ch;
+ const int channels =
+ readl_relaxed_bitfield(&mhuv2->reg.recv->MHU_CFG, NUM_CH);
+
+ msg->data = kzalloc(MHUV2_STAT_BYTES * channels, GFP_KERNEL);
+
+ for (ch = 0; ch < channels; ch++) {
+ /*
+ * Messages are expected to be received in order of most
+ * significant word to least significant word.
+ * (see mhuv2_send_data_multi_word)
+ */
+ const mhuv2_stat_reg_t word =
+ readl_relaxed(&mhuv2->reg.recv->channel[ch].STAT);
+ ((mhuv2_stat_reg_t *)msg->data)[channels - 1 - ch] = word;
+ }
+
+ msg->len = channels * MHUV2_STAT_BYTES;
+ return 0;
+}
+
+static inline int mhuv2_clear_data_multi_word(struct arm_mhuv2 *mhuv2,
+ struct mbox_chan *chan,
+ struct arm_mbox_msg *msg)
+{
+ int ch;
+ const int channels =
+ readl_relaxed_bitfield(&mhuv2->reg.recv->MHU_CFG, NUM_CH);
+
+ for (ch = 0; ch < channels; ch++) {
+ /*
+ * Last channel window must be cleared as the final operation.
+ * Upon clearing the last channel window register, which is
+ * unmasked in multi-word mode, the interrupt is deasserted.
+ */
+ writel_relaxed(
+ readl_relaxed(&mhuv2->reg.recv->channel[ch].STAT),
+ &mhuv2->reg.recv->channel[ch].STAT_CLEAR);
+ }
+ return 0;
+}
+
+static inline int __mhuv2_mw_bytes_to_send(const int bytes_in_round,
+ const int bytes_left)
+{
+ /*
+ * Bytes to send on the current channel will always be MHUV2_STAT_BYTES
+ * unless in the last round and
+ * msg->len % MHUV2_STAT_BYTES != 0
+ */
+ if (bytes_in_round % MHUV2_STAT_BYTES != 0) {
+ const int bts = bytes_left % MHUV2_STAT_BYTES;
+ return bts == 0 ? MHUV2_STAT_BYTES : bts;
+ } else {
+ return MHUV2_STAT_BYTES;
+ }
+}
+
+static inline int mhuv2_send_data_multi_word(struct arm_mhuv2 *mhuv2,
+ struct mbox_chan *chan,
+ const struct arm_mbox_msg *msg)
+{
+ /*
+ * Message will be transmitted from most significant to least
+ * significant word. This is to allow for messages shorter than
+ * $channels to still trigger the receiver interrupt which gets
+ * activated when the last STAT register is written. As an example, a
+ * 6-word message is to be written on a 4-channel MHU connection:
+ * Registers marked with '*' are masked, and will not generate an
+ * interrupt on the receiver side once written.
+ *
+ * uint32_t *data = [0x00000001],[0x00000002],[0x00000003],[0x00000004],
+ * [0x00000005], [0x00000006]
+ *
+ * ROUND 1:
+ * STAT reg To write Write sequence
+ * [ STAT 3 ] <- [0x00000001] 4 <- triggers interrupt on receiver
+ * *[ STAT 2 ] <- [0x00000002] 3
+ * *[ STAT 1 ] <- [0x00000003] 2
+ * *[ STAT 0 ] <- [0x00000004] 1
+ *
+ * data += 4 // Increment data pointer by number of STAT regs
+ *
+ * ROUND 2:
+ * STAT reg To write Write sequence
+ * [ STAT 3 ] <- [0x00000005] 2 <- triggers interrupt on receiver
+ * *[ STAT 2 ] <- [0x00000006] 1
+ * *[ STAT 1 ] <- [0x00000000]
+ * *[ STAT 0 ] <- [0x00000000]
+ */
+ int bytes_left, bytes_to_send, i, ch_idx;
+ const int ch_windows =
+ readl_relaxed_bitfield(&mhuv2->reg.recv->MHU_CFG, NUM_CH);
+ const size_t round_capacity = ch_windows * MHUV2_STAT_BYTES;
+
+ bytes_left = msg->len;
+ mhuv2_stat_reg_t *data = msg->data;
+
+ while (bytes_left > 0) {
+ /* Note: Each entry of this loop indicates a new ROUND */
+ if (*(u32 *)data == 0) {
+ dev_err(mhuv2->dev,
+ "values in *data aligned on NUM_STAT boundaries must not be zero to ensure that receiver interrupt is triggered\n",
+ ch_windows);
+ return -EINVAL;
+ }
+
+ const int bytes_in_round = bytes_left > round_capacity ?
+ round_capacity :
+ bytes_left;
+
+ for (i = (ch_windows - 1); i >= 0; i--) {
+ ch_idx = ch_windows - 1 - i;
+ /*
+ * Check whether data should be transmitted in register
+ * of index 'ch'.
+ */
+ if (bytes_in_round > (i * MHUV2_STAT_BYTES)) {
+ mhuv2_stat_reg_t word = data[i];
+
+ bytes_to_send = __mhuv2_mw_bytes_to_send(
+ bytes_in_round, bytes_left);
+
+ if (bytes_to_send != MHUV2_STAT_BYTES) {
+ word &= LSB_MASK(bytes_to_send *
+ __CHAR_BIT__);
+ }
+ while (readl_relaxed(
+ &mhuv2->reg.send->channel[ch_idx]
+ .STAT) != 0)
+ continue;
+
+ writel_relaxed(
+ word,
+ &mhuv2->reg.send->channel[ch_idx].STAT_SET);
+ bytes_left -= bytes_to_send;
+ }
+ }
+
+ data += ch_windows;
+
+ for (ch_idx = 0; ch_idx < ch_windows; ch_idx++) {
+ while (readl_relaxed(
+ &mhuv2->reg.send->channel[ch_idx].STAT) != 0)
+ continue;
+ }
+ }
+ return 0;
+}
+
+
+static inline int mhuv2_last_tx_done_multi_word(struct arm_mhuv2 *mhuv2,
+ struct mbox_chan *chan)
+{
+ int ch_idx;
+ bool tx_done = true;
+
+ for (ch_idx = 0;
+ ch_idx < readl_relaxed_bitfield(&mhuv2->reg.send->MHU_CFG, NUM_CH);
+ ch_idx++) {
+ tx_done &= readl_relaxed(
+ &mhuv2->reg.send->channel[ch_idx].STAT) == 0;
+ }
+ return tx_done;
+}
+
+static inline int mhuv2_setup_multi_word(struct arm_mhuv2 *mhuv2)
+{
+ int ret, i;
+
+ const u32 channel_windows =
+ readl_relaxed_bitfield(mhuv2->frame == RECEIVER_FRAME ?
+ &mhuv2->reg.recv->MHU_CFG :
+ &mhuv2->reg.send->MHU_CFG,
+ NUM_CH);
+ if (channel_windows < 2) {
+ dev_err(mhuv2->dev,
+ "Error: at least 2 MHU channel windows are required for using the multi-word transfer protocol");
+ return -ENODEV;
+ }
+
+ if (mhuv2->frame == RECEIVER_FRAME) {
+ /*
+ * The multi-word transport protocol mandates that all but
+ * the last status register must be masked.
+ */
+ for (i = 0; i < (channel_windows - 1); i++) {
+ writel_relaxed(-1,
+ &mhuv2->reg.recv->channel[i].MASK_SET);
+ }
+ }
+
+ mhuv2->mbox.num_chans = 1;
+ mhuv2->mbox.chans =
+ devm_kzalloc(mhuv2->dev,
+ mhuv2->mbox.num_chans * sizeof(struct mbox_chan),
+ GFP_KERNEL);
+
+ return 0;
+}
+
+static inline struct mbox_chan *
+ mhuv2_get_active_mbox_chan_multi_word(struct arm_mhuv2 *mhuv2)
+{
+ return &mhuv2->mbox.chans[0];
+}
+
+static const struct mhuv2_ops mhuv2_multi_word_ops = {
+ .read_data = mhuv2_read_data_multi_word,
+ .clear_data = mhuv2_clear_data_multi_word,
+ .send_data = mhuv2_send_data_multi_word,
+ .setup = mhuv2_setup_multi_word,
+ .last_tx_done = mhuv2_last_tx_done_multi_word,
+ .get_active_mbox_chan = mhuv2_get_active_mbox_chan_multi_word,
+};
+/* ========================================================================== */
+
/* =================== Doorbell transport protocol operations =============== */
static inline int mhuv2_read_data_doorbell(struct arm_mhuv2 *mhuv2,
@@ -740,6 +962,9 @@ static int mhuv2_probe(struct amba_device *adev, const struct amba_id *id)
/* Assign transport protocol-specific operations */
switch (mhuv2->protocol) {
+ case MULTI_WORD:
+ mhuv2->ops = &mhuv2_multi_word_ops;
+ break;
case SINGLE_WORD:
mhuv2->ops = &mhuv2_single_word_ops;
break;
--
2.17.1
