ionic: get MTU from lif identity

Change from using hardcoded MTU limits and instead use the
firmware defined limits. The value from the LIF attributes is
the frame size, so we take off the header size to convert to
MTU size.
Signed-off-by: Shannon Nelson <snelson@pensando.io>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/pensando/ionic/ionic_dev.h

@@ -10,8 +10,6 @@
 #include "ionic_if.h"
 #include "ionic_regs.h"
 
-#define IONIC_MIN_MTU			ETH_MIN_MTU
-#define IONIC_MAX_MTU			9194
 #define IONIC_MAX_TX_DESC		8192
 #define IONIC_MAX_RX_DESC		16384
 #define IONIC_MIN_TXRX_DESC		16

drivers/net/ethernet/pensando/ionic/ionic_lif.c

@@ -5,6 +5,7 @@
 #include <linux/dynamic_debug.h>
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
+#include <linux/if_vlan.h>
 #include <linux/rtnetlink.h>
 #include <linux/interrupt.h>
 #include <linux/pci.h>
@@ -2022,11 +2023,16 @@ int ionic_reset_queues(struct ionic_lif *lif, ionic_reset_cb cb, void *arg)
 static struct ionic_lif *ionic_lif_alloc(struct ionic *ionic, unsigned int index)
 {
 	struct device *dev = ionic->dev;
+	union ionic_lif_identity *lid;
 	struct net_device *netdev;
 	struct ionic_lif *lif;
 	int tbl_sz;
 	int err;
 
+	lid = kzalloc(sizeof(*lid), GFP_KERNEL);
+	if (!lid)
+		return ERR_PTR(-ENOMEM);
+
 	netdev = alloc_etherdev_mqs(sizeof(*lif),
 				    ionic->ntxqs_per_lif, ionic->ntxqs_per_lif);
 	if (!netdev) {
@@ -2045,8 +2051,12 @@ static struct ionic_lif *ionic_lif_alloc(struct ionic *ionic, unsigned int index
 	netdev->watchdog_timeo = 2 * HZ;
 	netif_carrier_off(netdev);
 
-	netdev->min_mtu = IONIC_MIN_MTU;
-	netdev->max_mtu = IONIC_MAX_MTU;
+	lif->identity = lid;
+	lif->lif_type = IONIC_LIF_TYPE_CLASSIC;
+	ionic_lif_identify(ionic, lif->lif_type, lif->identity);
+	lif->netdev->min_mtu = le32_to_cpu(lif->identity->eth.min_frame_size);
+	lif->netdev->max_mtu =
+		le32_to_cpu(lif->identity->eth.max_frame_size) - ETH_HLEN - VLAN_HLEN;
 
 	lif->neqs = ionic->neqs_per_lif;
 	lif->nxqs = ionic->ntxqs_per_lif;
@@ -2113,6 +2123,7 @@ static struct ionic_lif *ionic_lif_alloc(struct ionic *ionic, unsigned int index
 err_out_free_netdev:
 	free_netdev(lif->netdev);
 	lif = NULL;
+	kfree(lid);
 
 	return ERR_PTR(err);
 }
@@ -2132,7 +2143,6 @@ int ionic_lifs_alloc(struct ionic *ionic)
 		return -ENOMEM;
 	}
 
-	lif->lif_type = IONIC_LIF_TYPE_CLASSIC;
 	ionic_lif_queue_identify(lif);
 
 	return 0;
@@ -2243,6 +2253,7 @@ static void ionic_lif_free(struct ionic_lif *lif)
 		ionic_lif_reset(lif);
 
 	/* free lif info */
+	kfree(lif->identity);
 	dma_free_coherent(dev, lif->info_sz, lif->info, lif->info_pa);
 	lif->info = NULL;
 	lif->info_pa = 0;

drivers/net/ethernet/pensando/ionic/ionic_lif.h

@@ -184,6 +184,7 @@ struct ionic_lif {
 	u16 lif_type;
 	unsigned int nucast;
 
+	union ionic_lif_identity *identity;
 	struct ionic_lif_info *info;
 	dma_addr_t info_pa;
 	u32 info_sz;