On Mon, Nov 1, 2021 at 6:57 AM Ricardo Martinez
[off-list ref] wrote:

Cross Layer DMA (CLDMA) Hardware interface (HIF) enables the control
path of Host-Modem data transfers. CLDMA HIF layer provides a common
interface to the Port Layer.

CLDMA manages 8 independent RX/TX physical channels with data flow
control in HW queues. CLDMA uses ring buffers of General Packet
Descriptors (GPD) for TX/RX. GPDs can represent multiple or single
data buffers (DB).

CLDMA HIF initializes GPD rings, registers ISR handlers for CLDMA
interrupts, and initializes CLDMA HW registers.

CLDMA TX flow:
1. Port Layer write
2. Get DB address
3. Configure GPD
4. Triggering processing via HW register write

CLDMA RX flow:
1. CLDMA HW sends a RX "done" to host
2. Driver starts thread to safely read GPD
3. DB is sent to Port layer
4. Create a new buffer for GPD ring

[skipped]

Place this pointers array to a private _device_ state structure.
Otherwise, with these global pointers, the driver will break as soon
as a second modem is connected to the host.

Also all corresponding functions should be reworked to be able to
accept a modem state container pointer.

+static DEFINE_MUTEX(ctl_cfg_mutex); /* protects CLDMA late init config */

Place this mutex to a private device state structure as well to avoid
useless inter-device locking and possible deadlocks.

+static enum cldma_queue_type rxq_type[CLDMA_RXQ_NUM];
+static enum cldma_queue_type txq_type[CLDMA_TXQ_NUM];
+static int rxq_buff_size[CLDMA_RXQ_NUM];
+static int rxq_buff_num[CLDMA_RXQ_NUM];
+static int txq_buff_num[CLDMA_TXQ_NUM];

If these arrays could be shared between modem instances (i.e. if this
is a some kind of static configuration) then initialize them
statically or in the module_init(). Otherwise, if these arrays are
part of the runtime state, then place them in a device state
container.

--
Sergey