can: c_can: prepare to up the message objects number

As pointed by commit c0a9f4d3 ("can: c_can: Reduce register
access") the "driver casts the 16 message objects in stone, which is
completely braindead as contemporary hardware has up to 128 message
objects".

The patch prepares the module to extend the number of message objects
beyond the 32 currently managed. This was achieved by transforming the
constants used to manage RX/TX messages into variables without
changing the driver policy.
Reported-by: kernel test robot <lkp@intel.com>
Link: https://lore.kernel.org/r/20210302215435.18286-6-dariobin@libero.itSigned-off-by: Dario Binacchi <dariobin@libero.it>
Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

drivers/net/can/c_can/c_can.c

@@ -170,9 +170,6 @@
 /* Wait for ~1 sec for INIT bit */
 #define INIT_WAIT_MS		1000
 
-/* napi related */
-#define C_CAN_NAPI_WEIGHT	C_CAN_MSG_OBJ_RX_NUM
-
 /* c_can lec values */
 enum c_can_lec_type {
 	LEC_NO_ERROR = 0,
@@ -306,7 +303,7 @@ static void c_can_setup_tx_object(struct net_device *dev, int iface,
 	 * first, i.e. clear the MSGVAL flag in the arbiter.
 	 */
 	if (rtr != (bool)test_bit(idx, &priv->tx_dir)) {
-		u32 obj = idx + C_CAN_MSG_OBJ_TX_FIRST;
+		u32 obj = idx + priv->msg_obj_tx_first;
 
 		c_can_inval_msg_object(dev, iface, obj);
 		change_bit(idx, &priv->tx_dir);
@@ -443,10 +440,10 @@ static netdev_tx_t c_can_start_xmit(struct sk_buff *skb,
 	 * prioritized. The lowest buffer number wins.
 	 */
 	idx = fls(atomic_read(&priv->tx_active));
-	obj = idx + C_CAN_MSG_OBJ_TX_FIRST;
+	obj = idx + priv->msg_obj_tx_first;
 
 	/* If this is the last buffer, stop the xmit queue */
-	if (idx == C_CAN_MSG_OBJ_TX_NUM - 1)
+	if (idx == priv->msg_obj_tx_num - 1)
 		netif_stop_queue(dev);
 	/* Store the message in the interface so we can call
 	 * can_put_echo_skb(). We must do this before we enable
@@ -527,17 +524,18 @@ static int c_can_set_bittiming(struct net_device *dev)
  */
 static void c_can_configure_msg_objects(struct net_device *dev)
 {
+	struct c_can_priv *priv = netdev_priv(dev);
 	int i;
 
 	/* first invalidate all message objects */
-	for (i = C_CAN_MSG_OBJ_RX_FIRST; i <= C_CAN_NO_OF_OBJECTS; i++)
+	for (i = priv->msg_obj_rx_first; i <= priv->msg_obj_num; i++)
 		c_can_inval_msg_object(dev, IF_RX, i);
 
 	/* setup receive message objects */
-	for (i = C_CAN_MSG_OBJ_RX_FIRST; i < C_CAN_MSG_OBJ_RX_LAST; i++)
+	for (i = priv->msg_obj_rx_first; i < priv->msg_obj_rx_last; i++)
 		c_can_setup_receive_object(dev, IF_RX, i, 0, 0, IF_MCONT_RCV);
 
-	c_can_setup_receive_object(dev, IF_RX, C_CAN_MSG_OBJ_RX_LAST, 0, 0,
+	c_can_setup_receive_object(dev, IF_RX, priv->msg_obj_rx_last, 0, 0,
 				   IF_MCONT_RCV_EOB);
 }
 
@@ -708,7 +706,7 @@ static void c_can_do_tx(struct net_device *dev)
 	while ((idx = ffs(pend))) {
 		idx--;
 		pend &= ~(1 << idx);
-		obj = idx + C_CAN_MSG_OBJ_TX_FIRST;
+		obj = idx + priv->msg_obj_tx_first;
 
 		/* We use IF_RX interface instead of IF_TX because we
 		 * are called from c_can_poll(), which runs inside
@@ -723,7 +721,7 @@ static void c_can_do_tx(struct net_device *dev)
 	/* Clear the bits in the tx_active mask */
 	atomic_sub(clr, &priv->tx_active);
 
-	if (clr & (1 << (C_CAN_MSG_OBJ_TX_NUM - 1)))
+	if (clr & (1 << (priv->msg_obj_tx_num - 1)))
 		netif_wake_queue(dev);
 
 	if (pkts) {
@@ -737,11 +735,11 @@ static void c_can_do_tx(struct net_device *dev)
  * raced with the hardware or failed to readout all upper
  * objects in the last run due to quota limit.
  */
-static u32 c_can_adjust_pending(u32 pend)
+static u32 c_can_adjust_pending(u32 pend, u32 rx_mask)
 {
 	u32 weight, lasts;
 
-	if (pend == RECEIVE_OBJECT_BITS)
+	if (pend == rx_mask)
 		return pend;
 
 	/* If the last set bit is larger than the number of pending
@@ -840,8 +838,7 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota)
 	/* It is faster to read only one 16bit register. This is only possible
 	 * for a maximum number of 16 objects.
 	 */
-	BUILD_BUG_ON_MSG(C_CAN_MSG_OBJ_RX_LAST > 16,
-			 "Implementation does not support more message objects than 16");
+	WARN_ON(priv->msg_obj_rx_last > 16);
 
 	while (quota > 0) {
 		if (!pend) {
@@ -851,7 +848,8 @@ static int c_can_do_rx_poll(struct net_device *dev, int quota)
 			/* If the pending field has a gap, handle the
 			 * bits above the gap first.
 			 */
-			toread = c_can_adjust_pending(pend);
+			toread = c_can_adjust_pending(pend,
+						      priv->msg_obj_rx_mask);
 		} else {
 			toread = pend;
 		}
@@ -1181,17 +1179,31 @@ static int c_can_close(struct net_device *dev)
 	return 0;
 }
 
-struct net_device *alloc_c_can_dev(void)
+struct net_device *alloc_c_can_dev(int msg_obj_num)
 {
 	struct net_device *dev;
 	struct c_can_priv *priv;
+	int msg_obj_tx_num = msg_obj_num / 2;
 
-	dev = alloc_candev(sizeof(struct c_can_priv), C_CAN_MSG_OBJ_TX_NUM);
+	dev = alloc_candev(struct_size(priv, dlc, msg_obj_tx_num),
+			   msg_obj_tx_num);
 	if (!dev)
 		return NULL;
 
 	priv = netdev_priv(dev);
-	netif_napi_add(dev, &priv->napi, c_can_poll, C_CAN_NAPI_WEIGHT);
+	priv->msg_obj_num = msg_obj_num;
+	priv->msg_obj_rx_num = msg_obj_num - msg_obj_tx_num;
+	priv->msg_obj_rx_first = 1;
+	priv->msg_obj_rx_last =
+		priv->msg_obj_rx_first + priv->msg_obj_rx_num - 1;
+	priv->msg_obj_rx_mask = GENMASK(priv->msg_obj_rx_num - 1, 0);
+
+	priv->msg_obj_tx_num = msg_obj_tx_num;
+	priv->msg_obj_tx_first = priv->msg_obj_rx_last + 1;
+	priv->msg_obj_tx_last =
+		priv->msg_obj_tx_first + priv->msg_obj_tx_num - 1;
+
+	netif_napi_add(dev, &priv->napi, c_can_poll, priv->msg_obj_rx_num);
 
 	priv->dev = dev;
 	priv->can.bittiming_const = &c_can_bittiming_const;

drivers/net/can/c_can/c_can.h

@@ -22,18 +22,7 @@
 #ifndef C_CAN_H
 #define C_CAN_H
 
-/* message object split */
 #define C_CAN_NO_OF_OBJECTS	32
-#define C_CAN_MSG_OBJ_RX_NUM	16
-#define C_CAN_MSG_OBJ_TX_NUM	16
-
-#define C_CAN_MSG_OBJ_RX_FIRST	1
-#define C_CAN_MSG_OBJ_RX_LAST	(C_CAN_MSG_OBJ_RX_FIRST + \
-				C_CAN_MSG_OBJ_RX_NUM - 1)
-
-#define C_CAN_MSG_OBJ_TX_FIRST	(C_CAN_MSG_OBJ_RX_LAST + 1)
-
-#define RECEIVE_OBJECT_BITS	0x0000ffff
 
 enum reg {
 	C_CAN_CTRL_REG = 0,
@@ -193,6 +182,14 @@ struct c_can_priv {
 	struct napi_struct napi;
 	struct net_device *dev;
 	struct device *device;
+	unsigned int msg_obj_num;
+	unsigned int msg_obj_rx_num;
+	unsigned int msg_obj_tx_num;
+	unsigned int msg_obj_rx_first;
+	unsigned int msg_obj_rx_last;
+	unsigned int msg_obj_tx_first;
+	unsigned int msg_obj_tx_last;
+	u32 msg_obj_rx_mask;
 	atomic_t tx_active;
 	atomic_t sie_pending;
 	unsigned long tx_dir;
@@ -209,10 +206,10 @@ struct c_can_priv {
 	void (*raminit)(const struct c_can_priv *priv, bool enable);
 	u32 comm_rcv_high;
 	u32 rxmasked;
-	u32 dlc[C_CAN_MSG_OBJ_TX_NUM];
+	u32 dlc[];
 };
 
-struct net_device *alloc_c_can_dev(void);
+struct net_device *alloc_c_can_dev(int msg_obj_num);
 void free_c_can_dev(struct net_device *dev);
 int register_c_can_dev(struct net_device *dev);
 void unregister_c_can_dev(struct net_device *dev);

drivers/net/can/c_can/c_can_pci.c

@@ -147,7 +147,7 @@ static int c_can_pci_probe(struct pci_dev *pdev,
 	}
 
 	/* allocate the c_can device */
-	dev = alloc_c_can_dev();
+	dev = alloc_c_can_dev(C_CAN_NO_OF_OBJECTS);
 	if (!dev) {
 		ret = -ENOMEM;
 		goto out_iounmap;

drivers/net/can/c_can/c_can_platform.c

@@ -294,7 +294,7 @@ static int c_can_plat_probe(struct platform_device *pdev)
 	}
 
 	/* allocate the c_can device */
-	dev = alloc_c_can_dev();
+	dev = alloc_c_can_dev(C_CAN_NO_OF_OBJECTS);
 	if (!dev) {
 		ret = -ENOMEM;
 		goto exit;