Fixed MTP to work with TWRP

net/caif/cffrml.c

@@ -0,0 +1,197 @@
+/*
+ * CAIF Framing Layer.
+ *
+ * Copyright (C) ST-Ericsson AB 2010
+ * Author:	Sjur Brendeland
+ * License terms: GNU General Public License (GPL) version 2
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ":%s(): " fmt, __func__
+
+#include <linux/stddef.h>
+#include <linux/spinlock.h>
+#include <linux/slab.h>
+#include <linux/crc-ccitt.h>
+#include <linux/netdevice.h>
+#include <net/caif/caif_layer.h>
+#include <net/caif/cfpkt.h>
+#include <net/caif/cffrml.h>
+
+#define container_obj(layr) container_of(layr, struct cffrml, layer)
+
+struct cffrml {
+	struct cflayer layer;
+	bool dofcs;		/* !< FCS active */
+	int __percpu		*pcpu_refcnt;
+};
+
+static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt);
+static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt);
+static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
+			   int phyid);
+
+static u32 cffrml_rcv_error;
+static u32 cffrml_rcv_checsum_error;
+struct cflayer *cffrml_create(u16 phyid, bool use_fcs)
+{
+	struct cffrml *this = kzalloc(sizeof(struct cffrml), GFP_ATOMIC);
+	if (!this)
+		return NULL;
+	this->pcpu_refcnt = alloc_percpu(int);
+	if (this->pcpu_refcnt == NULL) {
+		kfree(this);
+		return NULL;
+	}
+
+	caif_assert(offsetof(struct cffrml, layer) == 0);
+
+	this->layer.receive = cffrml_receive;
+	this->layer.transmit = cffrml_transmit;
+	this->layer.ctrlcmd = cffrml_ctrlcmd;
+	snprintf(this->layer.name, CAIF_LAYER_NAME_SZ, "frm%d", phyid);
+	this->dofcs = use_fcs;
+	this->layer.id = phyid;
+	return (struct cflayer *) this;
+}
+
+void cffrml_free(struct cflayer *layer)
+{
+	struct cffrml *this = container_obj(layer);
+	free_percpu(this->pcpu_refcnt);
+	kfree(layer);
+}
+
+void cffrml_set_uplayer(struct cflayer *this, struct cflayer *up)
+{
+	this->up = up;
+}
+
+void cffrml_set_dnlayer(struct cflayer *this, struct cflayer *dn)
+{
+	this->dn = dn;
+}
+
+static u16 cffrml_checksum(u16 chks, void *buf, u16 len)
+{
+	/* FIXME: FCS should be moved to glue in order to use OS-Specific
+	 * solutions
+	 */
+	return crc_ccitt(chks, buf, len);
+}
+
+static int cffrml_receive(struct cflayer *layr, struct cfpkt *pkt)
+{
+	u16 tmp;
+	u16 len;
+	u16 hdrchks;
+	u16 pktchks;
+	struct cffrml *this;
+	this = container_obj(layr);
+
+	cfpkt_extr_head(pkt, &tmp, 2);
+	len = le16_to_cpu(tmp);
+
+	/* Subtract for FCS on length if FCS is not used. */
+	if (!this->dofcs)
+		len -= 2;
+
+	if (cfpkt_setlen(pkt, len) < 0) {
+		++cffrml_rcv_error;
+		pr_err("Framing length error (%d)\n", len);
+		cfpkt_destroy(pkt);
+		return -EPROTO;
+	}
+	/*
+	 * Don't do extract if FCS is false, rather do setlen - then we don't
+	 * get a cache-miss.
+	 */
+	if (this->dofcs) {
+		cfpkt_extr_trail(pkt, &tmp, 2);
+		hdrchks = le16_to_cpu(tmp);
+		pktchks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
+		if (pktchks != hdrchks) {
+			cfpkt_add_trail(pkt, &tmp, 2);
+			++cffrml_rcv_error;
+			++cffrml_rcv_checsum_error;
+			pr_info("Frame checksum error (0x%x != 0x%x)\n",
+				hdrchks, pktchks);
+			return -EILSEQ;
+		}
+	}
+	if (cfpkt_erroneous(pkt)) {
+		++cffrml_rcv_error;
+		pr_err("Packet is erroneous!\n");
+		cfpkt_destroy(pkt);
+		return -EPROTO;
+	}
+
+	if (layr->up == NULL) {
+		pr_err("Layr up is missing!\n");
+		cfpkt_destroy(pkt);
+		return -EINVAL;
+	}
+
+	return layr->up->receive(layr->up, pkt);
+}
+
+static int cffrml_transmit(struct cflayer *layr, struct cfpkt *pkt)
+{
+	u16 chks;
+	u16 len;
+	__le16 data;
+
+	struct cffrml *this = container_obj(layr);
+	if (this->dofcs) {
+		chks = cfpkt_iterate(pkt, cffrml_checksum, 0xffff);
+		data = cpu_to_le16(chks);
+		cfpkt_add_trail(pkt, &data, 2);
+	} else {
+		cfpkt_pad_trail(pkt, 2);
+	}
+	len = cfpkt_getlen(pkt);
+	data = cpu_to_le16(len);
+	cfpkt_add_head(pkt, &data, 2);
+	cfpkt_info(pkt)->hdr_len += 2;
+	if (cfpkt_erroneous(pkt)) {
+		pr_err("Packet is erroneous!\n");
+		cfpkt_destroy(pkt);
+		return -EPROTO;
+	}
+
+	if (layr->dn == NULL) {
+		cfpkt_destroy(pkt);
+		return -ENODEV;
+
+	}
+	return layr->dn->transmit(layr->dn, pkt);
+}
+
+static void cffrml_ctrlcmd(struct cflayer *layr, enum caif_ctrlcmd ctrl,
+			   int phyid)
+{
+	if (layr->up && layr->up->ctrlcmd)
+		layr->up->ctrlcmd(layr->up, ctrl, layr->id);
+}
+
+void cffrml_put(struct cflayer *layr)
+{
+	struct cffrml *this = container_obj(layr);
+	if (layr != NULL && this->pcpu_refcnt != NULL)
+		this_cpu_dec(*this->pcpu_refcnt);
+}
+
+void cffrml_hold(struct cflayer *layr)
+{
+	struct cffrml *this = container_obj(layr);
+	if (layr != NULL && this->pcpu_refcnt != NULL)
+		this_cpu_inc(*this->pcpu_refcnt);
+}
+
+int cffrml_refcnt_read(struct cflayer *layr)
+{
+	int i, refcnt = 0;
+	struct cffrml *this = container_obj(layr);
+	for_each_possible_cpu(i)
+		refcnt += *per_cpu_ptr(this->pcpu_refcnt, i);
+	return refcnt;
+}