[PATCH v4 2/3] nfc: st-nci: add raw NCI path for ST21NFCD

[Kristian Brox <isyourbrainfoss@proton.me>]

ST21NFCD does not use NDLC. When the compatible is st,st21nfcd,
talk raw NCI:

- do not add or strip an NDLC PCB
- do not run the T1/T2 ACK timers
- I2C reads are a 3-byte NCI header plus payload
- skip proprietary SET_NFC_MODE and HCI SE discovery
- consume proprietary RF NTF 0xf02 (GID 0xf, OID 0x02)

Set the raw_nci flag before nci_register_device so ndlc_send does
not push an NDLC PCB into a 0-headroom skb. Enable optional vdd-io
(VPS_IO) and SYS_CLK before driving reset.

Reset is active-low. Existing boards describe it as GPIO_ACTIVE_HIGH
and the driver treats gpiod_set_value(reset, 1) as chip-running.
Keep that path so old DTS is unchanged. If the GPIO is active-low,
pulse logical 1 then 0 (assert, then deassert).

Existing st21nfcb / st21nfcc boards keep the NDLC path and do not
need those properties.

Tested on Fairphone 5: adapter powers up and reads an NTAG 215.

Signed-off-by: Kristian Brox <isyourbrainfoss@proton.me>
---
 drivers/nfc/st-nci/core.c   | 22 ++++++++++++
 drivers/nfc/st-nci/i2c.c    | 82 ++++++++++++++++++++++++++++++++++++++++++---
 drivers/nfc/st-nci/ndlc.c   | 27 +++++++++++----
 drivers/nfc/st-nci/ndlc.h   |  5 ++-
 drivers/nfc/st-nci/se.c     |  3 ++
 drivers/nfc/st-nci/spi.c    |  2 +-
 drivers/nfc/st-nci/st-nci.h |  2 ++
 7 files changed, 129 insertions(+), 14 deletions(-)

diff --git a/drivers/nfc/st-nci/core.c b/drivers/nfc/st-nci/core.c
index a367136d4330..d7802434abda 100644
--- a/drivers/nfc/st-nci/core.c
+++ b/drivers/nfc/st-nci/core.c
@@ -18,8 +18,13 @@
 
 static int st_nci_init(struct nci_dev *ndev)
 {
+	struct st_nci_info *info = nci_get_drvdata(ndev);
 	struct nci_mode_set_cmd cmd;
 
+	/* ST21NFCD has no NDLC proprietary SET_NFC_MODE */
+	if (info->ndlc->raw_nci)
+		return 0;
+
 	cmd.cmd_type = ST_NCI_SET_NFC_MODE;
 	cmd.mode = 1;
 
@@ -84,12 +89,29 @@ static int st_nci_prop_rsp_packet(struct nci_dev *ndev,
 	return 0;
 }
 
+/*
+ * ST21NFCD emits proprietary NCI NTFs (GID 0xf, OID 0x02) on CORE_RESET
+ * and during each RF poll loop. The payload is an RF trace; tags are
+ * still reported with the standard RF_INTF_ACTIVATED_NTF. Consume the
+ * packet so nci_ntf_packet does not log "unsupported ntf opcode 0xf02".
+ */
+static int st_nci_prop_rf_ntf_packet(struct nci_dev *ndev,
+				     struct sk_buff *skb)
+{
+	return 0;
+}
+
 static const struct nci_driver_ops st_nci_prop_ops[] = {
 	{
 		.opcode = nci_opcode_pack(NCI_GID_PROPRIETARY,
 					  ST_NCI_CORE_PROP),
 		.rsp = st_nci_prop_rsp_packet,
 	},
+	{
+		.opcode = nci_opcode_pack(NCI_GID_PROPRIETARY,
+					  ST_NCI_PROP_RF_NTF),
+		.ntf = st_nci_prop_rf_ntf_packet,
+	},
 };
 
 static const struct nci_ops st_nci_ops = {
diff --git a/drivers/nfc/st-nci/i2c.c b/drivers/nfc/st-nci/i2c.c
index 152c20b6bb01..2ec029f31c67 100644
--- a/drivers/nfc/st-nci/i2c.c
+++ b/drivers/nfc/st-nci/i2c.c
@@ -10,10 +10,13 @@
 #include <linux/i2c.h>
 #include <linux/gpio/consumer.h>
 #include <linux/acpi.h>
+#include <linux/clk.h>
 #include <linux/interrupt.h>
 #include <linux/delay.h>
 #include <linux/nfc.h>
 #include <linux/of.h>
+#include <linux/property.h>
+#include <linux/regulator/consumer.h>
 
 #include "st-nci.h"
 
@@ -22,10 +25,17 @@
 /* ndlc header */
 #define ST_NCI_FRAME_HEADROOM 1
 #define ST_NCI_FRAME_TAILROOM 0
+#define ST_NCI_RAW_FRAME_HEADROOM 0
 
 #define ST_NCI_I2C_MIN_SIZE 4   /* PCB(1) + NCI Packet header(3) */
+#define ST_NCI_NCI_HDR_SIZE 3   /* raw NCI: MT/PBF/GID + OID + len */
 #define ST_NCI_I2C_MAX_SIZE 250 /* req 4.2.1 */
 
+enum st_nci_i2c_proto {
+	ST_NCI_I2C_PROTO_NDLC = 0,
+	ST_NCI_I2C_PROTO_RAW_NCI,
+};
+
 #define ST_NCI_DRIVER_NAME "st_nci"
 #define ST_NCI_I2C_DRIVER_NAME "st_nci_i2c"
 
@@ -34,6 +44,7 @@ struct st_nci_i2c_phy {
 	struct llt_ndlc *ndlc;
 
 	bool irq_active;
+	bool raw_nci;
 
 	struct gpio_desc *gpiod_reset;
 
@@ -44,9 +55,20 @@ static int st_nci_i2c_enable(void *phy_id)
 {
 	struct st_nci_i2c_phy *phy = phy_id;
 
-	gpiod_set_value(phy->gpiod_reset, 0);
-	usleep_range(10000, 15000);
-	gpiod_set_value(phy->gpiod_reset, 1);
+	/*
+	 * Existing DTS uses GPIO_ACTIVE_HIGH and treats logical 1 as
+	 * chip-running. GPIO_ACTIVE_LOW: logical 1 asserts reset
+	 * (physical LOW).
+	 */
+	if (gpiod_is_active_low(phy->gpiod_reset)) {
+		gpiod_set_value(phy->gpiod_reset, 1);
+		usleep_range(10000, 15000);
+		gpiod_set_value(phy->gpiod_reset, 0);
+	} else {
+		gpiod_set_value(phy->gpiod_reset, 0);
+		usleep_range(10000, 15000);
+		gpiod_set_value(phy->gpiod_reset, 1);
+	}
 	usleep_range(80000, 85000);
 
 	if (phy->ndlc->powered == 0 && phy->irq_active == 0) {
@@ -111,6 +133,42 @@ static int st_nci_i2c_read(struct st_nci_i2c_phy *phy,
 	u8 buf[ST_NCI_I2C_MAX_SIZE];
 	struct i2c_client *client = phy->i2c_dev;
 
+	if (phy->raw_nci) {
+		r = i2c_master_recv(client, buf, ST_NCI_NCI_HDR_SIZE);
+		if (r < 0) {
+			usleep_range(1000, 4000);
+			r = i2c_master_recv(client, buf, ST_NCI_NCI_HDR_SIZE);
+		}
+		if (r != ST_NCI_NCI_HDR_SIZE)
+			return -EREMOTEIO;
+
+		len = buf[2];
+		if (len > ST_NCI_I2C_MAX_SIZE) {
+			nfc_err(&client->dev, "invalid frame len\n");
+			return -EBADMSG;
+		}
+
+		*skb = alloc_skb(ST_NCI_NCI_HDR_SIZE + len, GFP_KERNEL);
+		if (!*skb)
+			return -ENOMEM;
+
+		skb_put(*skb, ST_NCI_NCI_HDR_SIZE);
+		memcpy((*skb)->data, buf, ST_NCI_NCI_HDR_SIZE);
+
+		if (!len)
+			return 0;
+
+		r = i2c_master_recv(client, buf, len);
+		if (r != len) {
+			kfree_skb(*skb);
+			return -EREMOTEIO;
+		}
+
+		skb_put(*skb, len);
+		memcpy((*skb)->data + ST_NCI_NCI_HDR_SIZE, buf, len);
+		return 0;
+	}
+
 	r = i2c_master_recv(client, buf, ST_NCI_I2C_MIN_SIZE);
 	if (r < 0) {  /* Retry, chip was in standby */
 		usleep_range(1000, 4000);
@@ -211,6 +269,8 @@ static int st_nci_i2c_probe(struct i2c_client *client)
 		return -ENOMEM;
 
 	phy->i2c_dev = client;
+	phy->raw_nci = (uintptr_t)device_get_match_data(dev) ==
+			ST_NCI_I2C_PROTO_RAW_NCI;
 
 	i2c_set_clientdata(client, phy);
 
@@ -218,6 +278,14 @@ static int st_nci_i2c_probe(struct i2c_client *client)
 	if (r)
 		dev_dbg(dev, "Unable to add GPIO mapping table\n");
 
+	r = devm_regulator_get_enable_optional(dev, "vdd-io");
+	if (r && r != -ENODEV)
+		return dev_err_probe(dev, r, "failed to enable vdd-io\n");
+
+	r = PTR_ERR_OR_ZERO(devm_clk_get_optional_enabled(dev, NULL));
+	if (r)
+		return dev_err_probe(dev, r, "failed to enable clock\n");
+
 	/* Get RESET GPIO */
 	phy->gpiod_reset = devm_gpiod_get(dev, "reset", GPIOD_OUT_HIGH);
 	if (IS_ERR(phy->gpiod_reset)) {
@@ -231,8 +299,10 @@ static int st_nci_i2c_probe(struct i2c_client *client)
 				device_property_read_bool(dev, "uicc-present");
 
 	r = ndlc_probe(phy, &i2c_phy_ops, &client->dev,
-			ST_NCI_FRAME_HEADROOM, ST_NCI_FRAME_TAILROOM,
-			&phy->ndlc, &phy->se_status);
+			phy->raw_nci ? ST_NCI_RAW_FRAME_HEADROOM :
+				       ST_NCI_FRAME_HEADROOM,
+			ST_NCI_FRAME_TAILROOM,
+			&phy->ndlc, &phy->se_status, phy->raw_nci);
 	if (r < 0) {
 		nfc_err(&client->dev, "Unable to register ndlc layer\n");
 		return r;
@@ -273,6 +343,8 @@ static const struct of_device_id of_st_nci_i2c_match[] = {
 	{ .compatible = "st,st21nfcb-i2c" },
 	{ .compatible = "st,st21nfcb_i2c" },
 	{ .compatible = "st,st21nfcc-i2c" },
+	{ .compatible = "st,st21nfcd",
+	  .data = (void *)ST_NCI_I2C_PROTO_RAW_NCI },
 	{ }
 };
 MODULE_DEVICE_TABLE(of, of_st_nci_i2c_match);
diff --git a/drivers/nfc/st-nci/ndlc.c b/drivers/nfc/st-nci/ndlc.c
index be4808859cfa..13026c4facb3 100644
--- a/drivers/nfc/st-nci/ndlc.c
+++ b/drivers/nfc/st-nci/ndlc.c
@@ -62,8 +62,9 @@ void ndlc_close(struct llt_ndlc *ndlc)
 	/* toggle reset pin */
 	ndlc->ops->enable(ndlc->phy_id);
 
-	nci_prop_cmd(ndlc->ndev, ST_NCI_CORE_PROP,
-		     sizeof(struct nci_mode_set_cmd), (__u8 *)&cmd);
+	if (!ndlc->raw_nci)
+		nci_prop_cmd(ndlc->ndev, ST_NCI_CORE_PROP,
+			     sizeof(struct nci_mode_set_cmd), (__u8 *)&cmd);
 
 	ndlc->powered = 0;
 	ndlc->ops->disable(ndlc->phy_id);
@@ -72,11 +73,13 @@ EXPORT_SYMBOL(ndlc_close);
 
 int ndlc_send(struct llt_ndlc *ndlc, struct sk_buff *skb)
 {
-	/* add ndlc header */
-	u8 pcb = PCB_TYPE_DATAFRAME | PCB_DATAFRAME_RETRANSMIT_NO |
-		PCB_FRAME_CRC_INFO_NOTPRESENT;
+	if (!ndlc->raw_nci) {
+		/* add ndlc header */
+		u8 pcb = PCB_TYPE_DATAFRAME | PCB_DATAFRAME_RETRANSMIT_NO |
+			PCB_FRAME_CRC_INFO_NOTPRESENT;
 
-	*(u8 *)skb_push(skb, 1) = pcb;
+		*(u8 *)skb_push(skb, 1) = pcb;
+	}
 	skb_queue_tail(&ndlc->send_q, skb);
 
 	schedule_work(&ndlc->sm_work);
@@ -103,6 +106,10 @@ static void llt_ndlc_send_queue(struct llt_ndlc *ndlc)
 			ndlc->hard_fault = r;
 			break;
 		}
+		if (ndlc->raw_nci) {
+			kfree_skb(skb);
+			continue;
+		}
 		time_sent = jiffies;
 		*(unsigned long *)skb->cb = time_sent;
 
@@ -154,6 +161,10 @@ static void llt_ndlc_rcv_queue(struct llt_ndlc *ndlc)
 		pr_debug("rcvQlen=%d\n", ndlc->rcv_q.qlen);
 
 	while ((skb = skb_dequeue(&ndlc->rcv_q)) != NULL) {
+		if (ndlc->raw_nci) {
+			nci_recv_frame(ndlc->ndev, skb);
+			continue;
+		}
 		pcb = skb->data[0];
 		skb_pull(skb, 1);
 		if ((pcb & PCB_TYPE_MASK) == PCB_TYPE_SUPERVISOR) {
@@ -251,7 +262,8 @@ static void ndlc_t2_timeout(struct timer_list *t)
 
 int ndlc_probe(void *phy_id, const struct nfc_phy_ops *phy_ops,
 	       struct device *dev, int phy_headroom, int phy_tailroom,
-	       struct llt_ndlc **ndlc_id, struct st_nci_se_status *se_status)
+	       struct llt_ndlc **ndlc_id, struct st_nci_se_status *se_status,
+	       bool raw_nci)
 {
 	struct llt_ndlc *ndlc;
 
@@ -263,6 +275,7 @@ int ndlc_probe(void *phy_id, const struct nfc_phy_ops *phy_ops,
 	ndlc->phy_id = phy_id;
 	ndlc->dev = dev;
 	ndlc->powered = 0;
+	ndlc->raw_nci = raw_nci;
 
 	*ndlc_id = ndlc;
 
diff --git a/drivers/nfc/st-nci/ndlc.h b/drivers/nfc/st-nci/ndlc.h
index c24ce9b0df52..0b12e12e47d2 100644
--- a/drivers/nfc/st-nci/ndlc.h
+++ b/drivers/nfc/st-nci/ndlc.h
@@ -39,6 +39,8 @@ struct llt_ndlc {
 	 */
 	int hard_fault;
 	int powered;
+	/* ST21NFCD: raw NCI on the wire, no NDLC PCB / ACK timers */
+	bool raw_nci;
 };
 
 int ndlc_open(struct llt_ndlc *ndlc);
@@ -47,6 +49,7 @@ int ndlc_send(struct llt_ndlc *ndlc, struct sk_buff *skb);
 void ndlc_recv(struct llt_ndlc *ndlc, struct sk_buff *skb);
 int ndlc_probe(void *phy_id, const struct nfc_phy_ops *phy_ops,
 	       struct device *dev, int phy_headroom, int phy_tailroom,
-	       struct llt_ndlc **ndlc_id, struct st_nci_se_status *se_status);
+	       struct llt_ndlc **ndlc_id, struct st_nci_se_status *se_status,
+	       bool raw_nci);
 void ndlc_remove(struct llt_ndlc *ndlc);
 #endif /* __LOCAL_NDLC_H__ */
diff --git a/drivers/nfc/st-nci/se.c b/drivers/nfc/st-nci/se.c
index 607ec768eb7b..44cc102bcde2 100644
--- a/drivers/nfc/st-nci/se.c
+++ b/drivers/nfc/st-nci/se.c
@@ -621,6 +621,9 @@ int st_nci_discover_se(struct nci_dev *ndev)
 	int se_count = 0;
 	struct st_nci_info *info = nci_get_drvdata(ndev);
 
+	if (info->ndlc->raw_nci)
+		return 0;
+
 	r = st_nci_hci_network_init(ndev);
 	if (r != 0)
 		return r;
diff --git a/drivers/nfc/st-nci/spi.c b/drivers/nfc/st-nci/spi.c
index 7948c7e0c88c..1ce80a85bfe6 100644
--- a/drivers/nfc/st-nci/spi.c
+++ b/drivers/nfc/st-nci/spi.c
@@ -246,7 +246,7 @@ static int st_nci_spi_probe(struct spi_device *dev)
 
 	r = ndlc_probe(phy, &spi_phy_ops, &dev->dev,
 			ST_NCI_FRAME_HEADROOM, ST_NCI_FRAME_TAILROOM,
-			&phy->ndlc, &phy->se_status);
+			&phy->ndlc, &phy->se_status, false);
 	if (r < 0) {
 		nfc_err(&dev->dev, "Unable to register ndlc layer\n");
 		return r;
diff --git a/drivers/nfc/st-nci/st-nci.h b/drivers/nfc/st-nci/st-nci.h
index 5286071e52cf..aa8782c95d2f 100644
--- a/drivers/nfc/st-nci/st-nci.h
+++ b/drivers/nfc/st-nci/st-nci.h
@@ -15,6 +15,8 @@
 
 #define ST_NCI_CORE_PROP                0x01
 #define ST_NCI_SET_NFC_MODE             0x02
+/* ST21NFCD proprietary RF activity / poll-trace notification (GID 0xf) */
+#define ST_NCI_PROP_RF_NTF		0x02
 
 /*
  * ref ISO7816-3 chap 8.1. the initial character TS is followed by a

-- 
2.55.0