[PATCH v8 0/3] greybus: Add BeaglePlay Greybus Driver

[PATCH v8 0/3] greybus: Add BeaglePlay Greybus Driver

[Ayush Singh]

BeagleConnect is both a technology concept and a line of board designs
that implement the technology. Born from Greybus, a mechanism for
dynamically extending a Linux system with embedded peripherals,
BeagleConnect adds two key elements: a 6LoWPAN transport and mikroBUS
manifests. The 6LoWPAN transport provides for arbitrary connections,
including the IEEE802.15.4g long-range wireless transport supported
between BeaglePlay and BeagleConnect Freedom (the first BeagleConnect
board design). The mikroBUS manifests provide for rapid prototyping
and low-node-count production with sensor boards following the
mikroBUS freely-licensable embedded bus standard such that existing
Linux drivers can be loaded upon Greybus discovery of the nodes.
This patch set provides the Linux-side hooks required for the 6LoWPAN
transport for BeagleConnect on BeaglePlay. Also adds required devicetree
additions.

Tested over `next-20230825`.

Link: https://programmershideaway.xyz/tags/gsoc23/ GSoC23 Blog
Link: https://git.beagleboard.org/gsoc/greybus/cc1352-firmware Zephyr App
Link: https://github.com/Ayush1325/linux/tree/gb-beagleplay GitHub Branch
Link: https://docs.beagleboard.org/latest/boards/beagleconnect/index.html BeagleConnect
Link: https://docs.beagleboard.org/latest/boards/beagleplay/index.html BeaglePlay
Link: https://github.com/Ayush1325/linux/tree/gb-beagleplay Github Repo
Link: https://lists.linaro.org/archives/list/greybus-dev@lists.linaro.org/thread/CBMC25GFHFOPHHKYRHG7UTJAOTONJKGV/ Patch v7

Changes in Patch v8
v7 -> v8:
- fix clocks
- fix reset-gpios
- depend on serdev

v6 -> v7:
- Drop speed variable
- Fix commit message
- add clock-names and descriptions
- fix power lines

v5 -> v6:
- Rename compatible to `ti,cc1352p7`
- Fix formatting
- Use kerneldoc
- Add clocks, power-gpios, reset-gpios to dt bindings

v4 -> v5:
- Move DT Bindings to net
- Rename compatible to `beagle,play-cc1352`
- Expose CC1352 as MCU
- Remove redundant tracing messages
- Fix memory leaks

v3 -> v4:
- Add DT Bindings
- Reorder commits
- Improve commit messages

v2 -> v3:
- Move gb-beagleplay out of staging

v1 -> v2:
- Combine the driver into a single file
- Remove redundant code
- Fix Checkpatch complaints
- Other suggested changes

Ayush Singh (3):
  dt-bindings: net: Add ti,cc1352p7
  greybus: Add BeaglePlay Linux Driver
  dts: ti: k3-am625-beagleplay: Add beaglecc1352

 .../devicetree/bindings/net/ti,cc1352p7.yaml  |  51 ++
 MAINTAINERS                                   |   7 +
 .../arm64/boot/dts/ti/k3-am625-beagleplay.dts |   4 +
 drivers/greybus/Kconfig                       |  10 +
 drivers/greybus/Makefile                      |   2 +
 drivers/greybus/gb-beagleplay.c               | 501 ++++++++++++++++++
 6 files changed, 575 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
 create mode 100644 drivers/greybus/gb-beagleplay.c


base-commit: 6269320850097903b30be8f07a5c61d9f7592393
-- 
2.41.0

[PATCH v8 1/3] dt-bindings: net: Add ti,cc1352p7

[Ayush Singh]

Add DT bindings for Texas Instruments Simplelink CC1352P7 wireless MCU

BeaglePlay has CC1352P7 co-processor connected to the main AM62 (running
Linux) over UART. In the BeagleConnect Technology, CC1352 is responsible
for handling 6LoWPAN communication with beagleconnect freedom nodes as
well as their discovery.

Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>
---
 .../devicetree/bindings/net/ti,cc1352p7.yaml  | 51 +++++++++++++++++++
 MAINTAINERS                                   |  6 +++
 2 files changed, 57 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/net/ti,cc1352p7.yaml

diff --git a/Documentation/devicetree/bindings/net/ti,cc1352p7.yaml b/Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
new file mode 100644
index 000000000000..742763e04543
--- /dev/null
+++ b/Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
@@ -0,0 +1,51 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/net/ti,cc1352p7.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Texas Instruments Simplelink CC1352P7 wireless MCU
+
+description:
+  The cc1352p7 mcu can be connected via SPI or UART.
+
+maintainers:
+  - Ayush Singh <ayushdevel1325@gmail.com>
+
+properties:
+  compatible:
+    const: ti,cc1352p7
+
+  clocks:
+    items:
+      - description: main system (mcu and peripherals) clock
+      - description: low-frequency system clock
+
+  clock-names:
+    items:
+      - const: sclk_hf
+      - const: sclk_lf
+
+  reset-gpios:
+    maxItems: 1
+
+  vdds-supply: true
+
+required:
+  - compatible
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/gpio/gpio.h>
+
+    serial {
+      mcu {
+        compatible = "ti,cc1352p7";
+        clocks = <&sclk_hf 0>, <&sclk_lf 25>;
+        clock-names = "sclk_hf", "sclk_lf";
+        reset-gpios = <&pio 35 GPIO_ACTIVE_LOW>;
+        vdds-supply = <&vdds>;
+      };
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 37b9626ee654..5467669d7963 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8969,6 +8969,12 @@ F:	drivers/staging/greybus/sdio.c
 F:	drivers/staging/greybus/spi.c
 F:	drivers/staging/greybus/spilib.c
 
+GREYBUS BEAGLEPLAY DRIVERS
+M:	Ayush Singh <ayushdevel1325@gmail.com>
+L:	greybus-dev@lists.linaro.org (moderated for non-subscribers)
+S:	Maintained
+F:	Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
+
 GREYBUS SUBSYSTEM
 M:	Johan Hovold <johan@kernel.org>
 M:	Alex Elder <elder@kernel.org>
-- 
2.41.0

[PATCH v8 2/3] greybus: Add BeaglePlay Linux Driver

[Ayush Singh]

Add the Greybus host driver for BeaglePlay board by BeagleBoard.org.

The current greybus setup involves running SVC in a user-space
application (GBridge) and using netlink to communicate with kernel
space. GBridge itself uses wpanusb kernel driver, so the greybus messages
travel from kernel space (gb_netlink) to user-space (GBridge) and then
back to kernel space (wpanusb) before reaching CC1352.

This driver directly communicates with CC1352 (running SVC Zephyr
application). Thus, it simplifies the complete greybus setup eliminating
user-space GBridge.

This driver is responsible for the following:
- Start SVC (CC1352) on driver load.
- Send/Receive Greybus messages to/from CC1352 using HDLC over UART.
- Print Logs from CC1352.
- Stop SVC (CC1352) on driver load.

Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>
---
 MAINTAINERS                     |   1 +
 drivers/greybus/Kconfig         |  10 +
 drivers/greybus/Makefile        |   2 +
 drivers/greybus/gb-beagleplay.c | 501 ++++++++++++++++++++++++++++++++
 4 files changed, 514 insertions(+)
 create mode 100644 drivers/greybus/gb-beagleplay.c

diff --git a/MAINTAINERS b/MAINTAINERS
index 5467669d7963..d87e30626a6a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -8974,6 +8974,7 @@ M:	Ayush Singh <ayushdevel1325@gmail.com>
 L:	greybus-dev@lists.linaro.org (moderated for non-subscribers)
 S:	Maintained
 F:	Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
+F:	drivers/greybus/gb-beagleplay.c
 
 GREYBUS SUBSYSTEM
 M:	Johan Hovold <johan@kernel.org>
diff --git a/drivers/greybus/Kconfig b/drivers/greybus/Kconfig
index 78ba3c3083d5..033d31dbf3b8 100644
--- a/drivers/greybus/Kconfig
+++ b/drivers/greybus/Kconfig
@@ -17,6 +17,16 @@ menuconfig GREYBUS
 
 if GREYBUS
 
+config GREYBUS_BEAGLEPLAY
+	tristate "Greybus BeaglePlay driver"
+	depends on SERIAL_DEV_BUS
+	help
+	  Select this option if you have a BeaglePlay where CC1352
+	  co-processor acts as Greybus SVC.
+
+	  To compile this code as a module, chose M here: the module
+	  will be called gb-beagleplay.ko
+
 config GREYBUS_ES2
 	tristate "Greybus ES3 USB host controller"
 	depends on USB
diff --git a/drivers/greybus/Makefile b/drivers/greybus/Makefile
index 9bccdd229aa2..d986e94f8897 100644
--- a/drivers/greybus/Makefile
+++ b/drivers/greybus/Makefile
@@ -18,6 +18,8 @@ obj-$(CONFIG_GREYBUS)		+= greybus.o
 # needed for trace events
 ccflags-y += -I$(src)
 
+obj-$(CONFIG_GREYBUS_BEAGLEPLAY)	+= gb-beagleplay.o
+
 # Greybus Host controller drivers
 gb-es2-y := es2.o
 
diff --git a/drivers/greybus/gb-beagleplay.c b/drivers/greybus/gb-beagleplay.c
new file mode 100644
index 000000000000..43318c1993ba
--- /dev/null
+++ b/drivers/greybus/gb-beagleplay.c
@@ -0,0 +1,501 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Beagleplay Linux Driver for Greybus
+ *
+ * Copyright (c) 2023 Ayush Singh <ayushdevel1325@gmail.com>
+ * Copyright (c) 2023 BeagleBoard.org Foundation
+ */
+
+#include <linux/gfp.h>
+#include <linux/greybus.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/printk.h>
+#include <linux/serdev.h>
+#include <linux/tty.h>
+#include <linux/tty_driver.h>
+#include <linux/greybus/hd.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/crc-ccitt.h>
+#include <linux/circ_buf.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#define RX_HDLC_PAYLOAD 256
+#define CRC_LEN 2
+#define MAX_RX_HDLC (1 + RX_HDLC_PAYLOAD + CRC_LEN)
+#define TX_CIRC_BUF_SIZE 1024
+
+#define ADDRESS_GREYBUS 0x01
+#define ADDRESS_DBG 0x02
+#define ADDRESS_CONTROL 0x03
+
+#define HDLC_FRAME 0x7E
+#define HDLC_ESC 0x7D
+#define HDLC_XOR 0x20
+
+#define CONTROL_SVC_START 0x01
+#define CONTROL_SVC_STOP 0x02
+
+/* The maximum number of CPorts supported by Greybus Host Device */
+#define GB_MAX_CPORTS 32
+
+/**
+ * struct gb_beagleplay - BeaglePlay Greybus driver
+ *
+ * @sd: underlying serdev device
+ *
+ * @gb_hd: greybus host device
+ *
+ * @tx_work: hdlc transmit work
+ * @tx_producer_lock: hdlc transmit data producer lock. acquired when appending data to buffer.
+ * @tx_consumer_lock: hdlc transmit data consumer lock. acquired when sending data over uart.
+ * @tx_circ_buf: hdlc transmit circular buffer.
+ * @tx_crc: hdlc transmit crc-ccitt fcs
+ *
+ * @rx_buffer_len: length of receive buffer filled.
+ * @rx_buffer: hdlc frame receive buffer
+ * @rx_in_esc: hdlc rx flag to indicate ESC frame
+ */
+struct gb_beagleplay {
+	struct serdev_device *sd;
+
+	struct gb_host_device *gb_hd;
+
+	struct work_struct tx_work;
+	spinlock_t tx_producer_lock;
+	spinlock_t tx_consumer_lock;
+	struct circ_buf tx_circ_buf;
+	u16 tx_crc;
+
+	u16 rx_buffer_len;
+	bool rx_in_esc;
+	u8 rx_buffer[MAX_RX_HDLC];
+};
+
+/**
+ * struct hdlc_payload - Structure to represent part of HDCL frame payload data.
+ *
+ * @len: buffer length in bytes
+ * @buf: payload buffer
+ */
+struct hdlc_payload {
+	u16 len;
+	void *buf;
+};
+
+static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len)
+{
+	u16 cport_id;
+	struct gb_operation_msg_hdr *hdr = (struct gb_operation_msg_hdr *)buf;
+
+	memcpy(&cport_id, hdr->pad, sizeof(cport_id));
+
+	dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received",
+		hdr->operation_id, hdr->type, cport_id, hdr->result);
+
+	greybus_data_rcvd(bg->gb_hd, cport_id, buf, len);
+}
+
+static void hdlc_rx_dbg_frame(const struct gb_beagleplay *bg, const char *buf, u16 len)
+{
+	dev_dbg(&bg->sd->dev, "CC1352 Log: %.*s", (int)len, buf);
+}
+
+/**
+ * hdlc_write() - Consume HDLC Buffer.
+ * @bg: beagleplay greybus driver
+ *
+ * Assumes that consumer lock has been acquired.
+ */
+static void hdlc_write(struct gb_beagleplay *bg)
+{
+	int written;
+	/* Start consuming HDLC data */
+	int head = smp_load_acquire(&bg->tx_circ_buf.head);
+	int tail = bg->tx_circ_buf.tail;
+	int count = CIRC_CNT_TO_END(head, tail, TX_CIRC_BUF_SIZE);
+	const unsigned char *buf = &bg->tx_circ_buf.buf[tail];
+
+	if (count > 0) {
+		written = serdev_device_write_buf(bg->sd, buf, count);
+
+		/* Finish consuming HDLC data */
+		smp_store_release(&bg->tx_circ_buf.tail, (tail + written) & (TX_CIRC_BUF_SIZE - 1));
+	}
+}
+
+/**
+ * hdlc_append() - Queue HDLC data for sending.
+ * @bg: beagleplay greybus driver
+ * @value: hdlc byte to transmit
+ *
+ * Assumes that producer lock as been acquired.
+ */
+static void hdlc_append(struct gb_beagleplay *bg, u8 value)
+{
+	int tail, head = bg->tx_circ_buf.head;
+
+	while (true) {
+		tail = READ_ONCE(bg->tx_circ_buf.tail);
+
+		if (CIRC_SPACE(head, tail, TX_CIRC_BUF_SIZE) >= 1) {
+			bg->tx_circ_buf.buf[head] = value;
+
+			/* Finish producing HDLC byte */
+			smp_store_release(&bg->tx_circ_buf.head,
+					  (head + 1) & (TX_CIRC_BUF_SIZE - 1));
+			return;
+		}
+		dev_warn(&bg->sd->dev, "Tx circ buf full");
+		usleep_range(3000, 5000);
+	}
+}
+
+static void hdlc_append_escaped(struct gb_beagleplay *bg, u8 value)
+{
+	if (value == HDLC_FRAME || value == HDLC_ESC) {
+		hdlc_append(bg, HDLC_ESC);
+		value ^= HDLC_XOR;
+	}
+	hdlc_append(bg, value);
+}
+
+static void hdlc_append_tx_frame(struct gb_beagleplay *bg)
+{
+	bg->tx_crc = 0xFFFF;
+	hdlc_append(bg, HDLC_FRAME);
+}
+
+static void hdlc_append_tx_u8(struct gb_beagleplay *bg, u8 value)
+{
+	bg->tx_crc = crc_ccitt(bg->tx_crc, &value, 1);
+	hdlc_append_escaped(bg, value);
+}
+
+static void hdlc_append_tx_buf(struct gb_beagleplay *bg, const u8 *buf, u16 len)
+{
+	size_t i;
+
+	for (i = 0; i < len; i++)
+		hdlc_append_tx_u8(bg, buf[i]);
+}
+
+static void hdlc_append_tx_crc(struct gb_beagleplay *bg)
+{
+	bg->tx_crc ^= 0xffff;
+	hdlc_append_escaped(bg, bg->tx_crc & 0xff);
+	hdlc_append_escaped(bg, (bg->tx_crc >> 8) & 0xff);
+}
+
+static void hdlc_transmit(struct work_struct *work)
+{
+	struct gb_beagleplay *bg = container_of(work, struct gb_beagleplay, tx_work);
+
+	spin_lock_bh(&bg->tx_consumer_lock);
+	hdlc_write(bg);
+	spin_unlock_bh(&bg->tx_consumer_lock);
+}
+
+static void hdlc_tx_frames(struct gb_beagleplay *bg, u8 address, u8 control,
+			   const struct hdlc_payload payloads[], size_t count)
+{
+	size_t i;
+
+	spin_lock(&bg->tx_producer_lock);
+
+	hdlc_append_tx_frame(bg);
+	hdlc_append_tx_u8(bg, address);
+	hdlc_append_tx_u8(bg, control);
+
+	for (i = 0; i < count; ++i)
+		hdlc_append_tx_buf(bg, payloads[i].buf, payloads[i].len);
+
+	hdlc_append_tx_crc(bg);
+	hdlc_append_tx_frame(bg);
+
+	spin_unlock(&bg->tx_producer_lock);
+
+	schedule_work(&bg->tx_work);
+}
+
+static void hdlc_tx_s_frame_ack(struct gb_beagleplay *bg)
+{
+	hdlc_tx_frames(bg, bg->rx_buffer[0], (bg->rx_buffer[1] >> 1) & 0x7, NULL, 0);
+}
+
+static void hdlc_rx_frame(struct gb_beagleplay *bg)
+{
+	u16 crc, len;
+	u8 ctrl, *buf;
+	u8 address = bg->rx_buffer[0];
+
+	crc = crc_ccitt(0xffff, bg->rx_buffer, bg->rx_buffer_len);
+	if (crc != 0xf0b8) {
+		dev_warn_ratelimited(&bg->sd->dev, "CRC failed from %02x: 0x%04x", address, crc);
+		return;
+	}
+
+	ctrl = bg->rx_buffer[1];
+	buf = &bg->rx_buffer[2];
+	len = bg->rx_buffer_len - 4;
+
+	/* I-Frame, send S-Frame ACK */
+	if ((ctrl & 1) == 0)
+		hdlc_tx_s_frame_ack(bg);
+
+	switch (address) {
+	case ADDRESS_DBG:
+		hdlc_rx_dbg_frame(bg, buf, len);
+		break;
+	case ADDRESS_GREYBUS:
+		hdlc_rx_greybus_frame(bg, buf, len);
+		break;
+	default:
+		dev_warn_ratelimited(&bg->sd->dev, "unknown frame %u", address);
+	}
+}
+
+static int hdlc_rx(struct gb_beagleplay *bg, const u8 *data, size_t count)
+{
+	size_t i;
+	u8 c;
+
+	for (i = 0; i < count; ++i) {
+		c = data[i];
+
+		switch (c) {
+		case HDLC_FRAME:
+			if (bg->rx_buffer_len)
+				hdlc_rx_frame(bg);
+
+			bg->rx_buffer_len = 0;
+			break;
+		case HDLC_ESC:
+			bg->rx_in_esc = true;
+			break;
+		default:
+			if (bg->rx_in_esc) {
+				c ^= 0x20;
+				bg->rx_in_esc = false;
+			}
+
+			if (bg->rx_buffer_len < MAX_RX_HDLC) {
+				bg->rx_buffer[bg->rx_buffer_len] = c;
+				bg->rx_buffer_len++;
+			} else {
+				dev_err_ratelimited(&bg->sd->dev, "RX Buffer Overflow");
+				bg->rx_buffer_len = 0;
+			}
+		}
+	}
+
+	return count;
+}
+
+static int hdlc_init(struct gb_beagleplay *bg)
+{
+	INIT_WORK(&bg->tx_work, hdlc_transmit);
+	spin_lock_init(&bg->tx_producer_lock);
+	spin_lock_init(&bg->tx_consumer_lock);
+	bg->tx_circ_buf.head = 0;
+	bg->tx_circ_buf.tail = 0;
+
+	bg->tx_circ_buf.buf = devm_kmalloc(&bg->sd->dev, TX_CIRC_BUF_SIZE, GFP_KERNEL);
+	if (!bg->tx_circ_buf.buf)
+		return -ENOMEM;
+
+	bg->rx_buffer_len = 0;
+	bg->rx_in_esc = false;
+
+	return 0;
+}
+
+static void hdlc_deinit(struct gb_beagleplay *bg)
+{
+	flush_work(&bg->tx_work);
+}
+
+static int gb_tty_receive(struct serdev_device *sd, const unsigned char *data, size_t count)
+{
+	struct gb_beagleplay *bg = serdev_device_get_drvdata(sd);
+
+	return hdlc_rx(bg, data, count);
+}
+
+static void gb_tty_wakeup(struct serdev_device *serdev)
+{
+	struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
+
+	schedule_work(&bg->tx_work);
+}
+
+static struct serdev_device_ops gb_beagleplay_ops = {
+	.receive_buf = gb_tty_receive,
+	.write_wakeup = gb_tty_wakeup,
+};
+
+static int gb_message_send(struct gb_host_device *hd, u16 cport, struct gb_message *msg, gfp_t mask)
+{
+	struct gb_beagleplay *bg = dev_get_drvdata(&hd->dev);
+	struct hdlc_payload payloads[2];
+
+	dev_dbg(&hd->dev, "Sending greybus message with Operation %u, Type: %X on Cport %u",
+		msg->header->operation_id, msg->header->type, cport);
+
+	if (msg->header->size > RX_HDLC_PAYLOAD)
+		return dev_err_probe(&hd->dev, -E2BIG, "Greybus message too big");
+
+	memcpy(msg->header->pad, &cport, sizeof(cport));
+
+	payloads[0].buf = msg->header;
+	payloads[0].len = sizeof(*msg->header);
+	payloads[1].buf = msg->payload;
+	payloads[1].len = msg->payload_size;
+
+	hdlc_tx_frames(bg, ADDRESS_GREYBUS, 0x03, payloads, 2);
+	greybus_message_sent(bg->gb_hd, msg, 0);
+
+	return 0;
+}
+
+static void gb_message_cancel(struct gb_message *message)
+{
+}
+
+static struct gb_hd_driver gb_hdlc_driver = { .message_send = gb_message_send,
+					      .message_cancel = gb_message_cancel };
+
+static void gb_beagleplay_start_svc(struct gb_beagleplay *bg)
+{
+	const u8 command = CONTROL_SVC_START;
+	const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
+
+	hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
+}
+
+static void gb_beagleplay_stop_svc(struct gb_beagleplay *bg)
+{
+	const u8 command = CONTROL_SVC_STOP;
+	const struct hdlc_payload payload = { .len = 1, .buf = (void *)&command };
+
+	hdlc_tx_frames(bg, ADDRESS_CONTROL, 0x03, &payload, 1);
+}
+
+static void gb_greybus_deinit(struct gb_beagleplay *bg)
+{
+	gb_hd_del(bg->gb_hd);
+	gb_hd_put(bg->gb_hd);
+}
+
+static int gb_greybus_init(struct gb_beagleplay *bg)
+{
+	int ret;
+
+	bg->gb_hd = gb_hd_create(&gb_hdlc_driver, &bg->sd->dev, TX_CIRC_BUF_SIZE, GB_MAX_CPORTS);
+	if (IS_ERR(bg->gb_hd)) {
+		dev_err(&bg->sd->dev, "Failed to create greybus host device");
+		return PTR_ERR(bg->gb_hd);
+	}
+
+	ret = gb_hd_add(bg->gb_hd);
+	if (ret) {
+		dev_err(&bg->sd->dev, "Failed to add greybus host device");
+		goto free_gb_hd;
+	}
+	dev_set_drvdata(&bg->gb_hd->dev, bg);
+
+	return 0;
+
+free_gb_hd:
+	gb_greybus_deinit(bg);
+	return ret;
+}
+
+static void gb_serdev_deinit(struct gb_beagleplay *bg)
+{
+	serdev_device_close(bg->sd);
+}
+
+static int gb_serdev_init(struct gb_beagleplay *bg)
+{
+	int ret;
+
+	serdev_device_set_drvdata(bg->sd, bg);
+	serdev_device_set_client_ops(bg->sd, &gb_beagleplay_ops);
+	ret = serdev_device_open(bg->sd);
+	if (ret)
+		return dev_err_probe(&bg->sd->dev, ret, "Unable to open serial device");
+
+	serdev_device_set_baudrate(bg->sd, 115200);
+	serdev_device_set_flow_control(bg->sd, false);
+
+	return 0;
+}
+
+static int gb_beagleplay_probe(struct serdev_device *serdev)
+{
+	int ret = 0;
+	struct gb_beagleplay *bg;
+
+	bg = devm_kmalloc(&serdev->dev, sizeof(*bg), GFP_KERNEL);
+	if (!bg)
+		return -ENOMEM;
+
+	bg->sd = serdev;
+	ret = gb_serdev_init(bg);
+	if (ret)
+		return ret;
+
+	ret = hdlc_init(bg);
+	if (ret)
+		goto free_serdev;
+
+	ret = gb_greybus_init(bg);
+	if (ret)
+		goto free_hdlc;
+
+	gb_beagleplay_start_svc(bg);
+
+	return 0;
+
+free_hdlc:
+	hdlc_deinit(bg);
+free_serdev:
+	gb_serdev_deinit(bg);
+	return ret;
+}
+
+static void gb_beagleplay_remove(struct serdev_device *serdev)
+{
+	struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
+
+	gb_greybus_deinit(bg);
+	gb_beagleplay_stop_svc(bg);
+	hdlc_deinit(bg);
+	gb_serdev_deinit(bg);
+}
+
+static const struct of_device_id gb_beagleplay_of_match[] = {
+	{
+		.compatible = "ti,cc1352p7",
+	},
+	{},
+};
+MODULE_DEVICE_TABLE(of, gb_beagleplay_of_match);
+
+static struct serdev_device_driver gb_beagleplay_driver = {
+	.probe = gb_beagleplay_probe,
+	.remove = gb_beagleplay_remove,
+	.driver = {
+		.name = "gb_beagleplay",
+		.of_match_table = gb_beagleplay_of_match,
+	},
+};
+
+module_serdev_device_driver(gb_beagleplay_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ayush Singh <ayushdevel1325@gmail.com>");
+MODULE_DESCRIPTION("A Greybus driver for BeaglePlay");
-- 
2.41.0

[PATCH v8 3/3] dts: ti: k3-am625-beagleplay: Add beaglecc1352

[Ayush Singh]

The BeaglePlay board by BeagleBoard.org has a CC1352P7 co-processor
connected to the main AM62 (running Linux) over UART. In the BeagleConnect
Technology, CC1352 is responsible for handling 6LoWPAN communication with
beagleconnect freedom nodes as well as their discovery.

This mcu is used by gb-beagleplay, a Greybus driver for BeaglePlay.

Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>
---
 arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts b/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
index 7cfdf562b53b..5160923b4dc2 100644
--- a/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
+++ b/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
@@ -870,6 +870,10 @@ &main_uart6 {
 	pinctrl-names = "default";
 	pinctrl-0 = <&wifi_debug_uart_pins_default>;
 	status = "okay";
+
+	mcu {
+		compatible = "ti,cc1352p7";
+	};
 };
 
 &dss {
-- 
2.41.0

Re: [PATCH v8 1/3] dt-bindings: net: Add ti,cc1352p7

[Krzysztof Kozlowski]

On 06/10/2023 06:10, Ayush Singh wrote:
> Add DT bindings for Texas Instruments Simplelink CC1352P7 wireless MCU
> 
> BeaglePlay has CC1352P7 co-processor connected to the main AM62 (running
> Linux) over UART. In the BeagleConnect Technology, CC1352 is responsible
> for handling 6LoWPAN communication with beagleconnect freedom nodes as
> well as their discovery.
> 
> Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>


Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>


---

This is an automated instruction, just in case, because many review tags
are being ignored. If you know the process, you can skip it (please do
not feel offended by me posting it here - no bad intentions intended).
If you do not know the process, here is a short explanation:

Please add Acked-by/Reviewed-by/Tested-by tags when posting new
versions, under or above your Signed-off-by tag. Tag is "received", when
provided in a message replied to you on the mailing list. Tools like b4
can help here. However, there's no need to repost patches *only* to add
the tags. The upstream maintainer will do that for tags received on the
version they apply.

https://elixir.bootlin.com/linux/v6.5-rc3/source/Documentation/process/submitting-patches.rst#L577

Best regards,
Krzysztof

Re: [PATCH v8 1/3] dt-bindings: net: Add ti,cc1352p7

[Nishanth Menon]

On 09:40-20231006, Ayush Singh wrote:
> Add DT bindings for Texas Instruments Simplelink CC1352P7 wireless MCU
> 
> BeaglePlay has CC1352P7 co-processor connected to the main AM62 (running
> Linux) over UART. In the BeagleConnect Technology, CC1352 is responsible
> for handling 6LoWPAN communication with beagleconnect freedom nodes as
> well as their discovery.
> 
> Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>
> ---

very minor comments follow:

>  .../devicetree/bindings/net/ti,cc1352p7.yaml  | 51 +++++++++++++++++++
>  MAINTAINERS                                   |  6 +++
>  2 files changed, 57 insertions(+)
>  create mode 100644 Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
> 
> diff --git a/Documentation/devicetree/bindings/net/ti,cc1352p7.yaml b/Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
> new file mode 100644
> index 000000000000..742763e04543
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
> @@ -0,0 +1,51 @@
> +# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/net/ti,cc1352p7.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: Texas Instruments Simplelink CC1352P7 wireless MCU
> +
> +description:
> +  The cc1352p7 mcu can be connected via SPI or UART.
 s/cc1352p7/CC1352P7
 s/mcu/MCU

> +
> +maintainers:
> +  - Ayush Singh <ayushdevel1325@gmail.com>
> +
> +properties:
> +  compatible:
> +    const: ti,cc1352p7
> +
> +  clocks:
> +    items:
> +      - description: main system (mcu and peripherals) clock
s/mcu/MCU
also I'd call it high-frequency clock to give explanation of what "hf"
means.

> +      - description: low-frequency system clock
> +
> +  clock-names:
> +    items:
> +      - const: sclk_hf
> +      - const: sclk_lf
> +
> +  reset-gpios:
> +    maxItems: 1
> +
> +  vdds-supply: true
> +
> +required:
> +  - compatible
> +
> +additionalProperties: false
> +
> +examples:
> +  - |
> +    #include <dt-bindings/gpio/gpio.h>
> +
> +    serial {
> +      mcu {
> +        compatible = "ti,cc1352p7";
> +        clocks = <&sclk_hf 0>, <&sclk_lf 25>;
> +        clock-names = "sclk_hf", "sclk_lf";
> +        reset-gpios = <&pio 35 GPIO_ACTIVE_LOW>;
> +        vdds-supply = <&vdds>;
> +      };
> +    };
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 37b9626ee654..5467669d7963 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8969,6 +8969,12 @@ F:	drivers/staging/greybus/sdio.c
>  F:	drivers/staging/greybus/spi.c
>  F:	drivers/staging/greybus/spilib.c
>  
> +GREYBUS BEAGLEPLAY DRIVERS
> +M:	Ayush Singh <ayushdevel1325@gmail.com>
> +L:	greybus-dev@lists.linaro.org (moderated for non-subscribers)
> +S:	Maintained
> +F:	Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
> +
>  GREYBUS SUBSYSTEM
>  M:	Johan Hovold <johan@kernel.org>
>  M:	Alex Elder <elder@kernel.org>
> -- 
> 2.41.0
> 

With those minor comments (if there is a need for a respin):

Reviewed-by: Nishanth Menon <nm@ti.com>

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D

Re: [PATCH v8 3/3] dts: ti: k3-am625-beagleplay: Add beaglecc1352

[Nishanth Menon]

On 09:40-20231006, Ayush Singh wrote:
> The BeaglePlay board by BeagleBoard.org has a CC1352P7 co-processor
> connected to the main AM62 (running Linux) over UART. In the BeagleConnect
> Technology, CC1352 is responsible for handling 6LoWPAN communication with
> beagleconnect freedom nodes as well as their discovery.
> 
> This mcu is used by gb-beagleplay, a Greybus driver for BeaglePlay.
> 
> Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>
> ---
>  arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts b/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
> index 7cfdf562b53b..5160923b4dc2 100644
> --- a/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
> +++ b/arch/arm64/boot/dts/ti/k3-am625-beagleplay.dts
> @@ -870,6 +870,10 @@ &main_uart6 {
>  	pinctrl-names = "default";
>  	pinctrl-0 = <&wifi_debug_uart_pins_default>;
>  	status = "okay";
> +
> +	mcu {
> +		compatible = "ti,cc1352p7";

I suggest to go ahead and describe the fixed regulator and clocks as in
the beagleplay schematics as well.

> +	};
>  };
>  
>  &dss {
> -- 
> 2.41.0
> 

-- 
Regards,
Nishanth Menon
Key (0xDDB5849D1736249D) / Fingerprint: F8A2 8693 54EB 8232 17A3  1A34 DDB5 849D 1736 249D

Re: [PATCH v8 2/3] greybus: Add BeaglePlay Linux Driver

[Ayush Singh]

Hello everyone, I would like to get some feedback on the driver patch 
before submitting the new version of this patch series.
> Add the Greybus host driver for BeaglePlay board by BeagleBoard.org.
>
> The current greybus setup involves running SVC in a user-space
> application (GBridge) and using netlink to communicate with kernel
> space. GBridge itself uses wpanusb kernel driver, so the greybus messages
> travel from kernel space (gb_netlink) to user-space (GBridge) and then
> back to kernel space (wpanusb) before reaching CC1352.
>
> This driver directly communicates with CC1352 (running SVC Zephyr
> application). Thus, it simplifies the complete greybus setup eliminating
> user-space GBridge.
>
> This driver is responsible for the following:
> - Start SVC (CC1352) on driver load.
> - Send/Receive Greybus messages to/from CC1352 using HDLC over UART.
> - Print Logs from CC1352.
> - Stop SVC (CC1352) on driver load.
>
> Signed-off-by: Ayush Singh <ayushdevel1325@gmail.com>
> ---
>   MAINTAINERS                     |   1 +
>   drivers/greybus/Kconfig         |  10 +
>   drivers/greybus/Makefile        |   2 +
>   drivers/greybus/gb-beagleplay.c | 501 ++++++++++++++++++++++++++++++++
>   4 files changed, 514 insertions(+)
>   create mode 100644 drivers/greybus/gb-beagleplay.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 5467669d7963..d87e30626a6a 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -8974,6 +8974,7 @@ M:	Ayush Singh <ayushdevel1325@gmail.com>
>   L:	greybus-dev@lists.linaro.org (moderated for non-subscribers)
>   S:	Maintained
>   F:	Documentation/devicetree/bindings/net/ti,cc1352p7.yaml
> +F:	drivers/greybus/gb-beagleplay.c
>   
>   GREYBUS SUBSYSTEM
>   M:	Johan Hovold <johan@kernel.org>
> diff --git a/drivers/greybus/Kconfig b/drivers/greybus/Kconfig
> index 78ba3c3083d5..033d31dbf3b8 100644
> --- a/drivers/greybus/Kconfig
> +++ b/drivers/greybus/Kconfig
> @@ -17,6 +17,16 @@ menuconfig GREYBUS
>   
>   if GREYBUS
>   
> +config GREYBUS_BEAGLEPLAY
> +	tristate "Greybus BeaglePlay driver"
> +	depends on SERIAL_DEV_BUS
> +	help
> +	  Select this option if you have a BeaglePlay where CC1352
> +	  co-processor acts as Greybus SVC.
> +
> +	  To compile this code as a module, chose M here: the module
> +	  will be called gb-beagleplay.ko
> +
>   config GREYBUS_ES2
>   	tristate "Greybus ES3 USB host controller"
>   	depends on USB
> diff --git a/drivers/greybus/Makefile b/drivers/greybus/Makefile
> index 9bccdd229aa2..d986e94f8897 100644
> --- a/drivers/greybus/Makefile
> +++ b/drivers/greybus/Makefile
> @@ -18,6 +18,8 @@ obj-$(CONFIG_GREYBUS)		+= greybus.o
>   # needed for trace events
>   ccflags-y += -I$(src)
>   
> +obj-$(CONFIG_GREYBUS_BEAGLEPLAY)	+= gb-beagleplay.o
> +
>   # Greybus Host controller drivers
>   gb-es2-y := es2.o
>   
> diff --git a/drivers/greybus/gb-beagleplay.c b/drivers/greybus/gb-beagleplay.c
> new file mode 100644
> index 000000000000..43318c1993ba
> --- /dev/null
> +++ b/drivers/greybus/gb-beagleplay.c
> @@ -0,0 +1,501 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * Beagleplay Linux Driver for Greybus
> + *
> + * Copyright (c) 2023 Ayush Singh <ayushdevel1325@gmail.com>
> + * Copyright (c) 2023 BeagleBoard.org Foundation
> + */
> +
> +#include <linux/gfp.h>
> +#include <linux/greybus.h>
> +#include <linux/module.h>
> +#include <linux/of.h>
> +#include <linux/printk.h>
> +#include <linux/serdev.h>
> +#include <linux/tty.h>
> +#include <linux/tty_driver.h>
> +#include <linux/greybus/hd.h>
> +#include <linux/init.h>
> +#include <linux/device.h>
> +#include <linux/crc-ccitt.h>
> +#include <linux/circ_buf.h>
> +#include <linux/types.h>
> +#include <linux/workqueue.h>
> +
> +#define RX_HDLC_PAYLOAD 256
> +#define CRC_LEN 2
> +#define MAX_RX_HDLC (1 + RX_HDLC_PAYLOAD + CRC_LEN)
> +#define TX_CIRC_BUF_SIZE 1024
> +
> +#define ADDRESS_GREYBUS 0x01
> +#define ADDRESS_DBG 0x02
> +#define ADDRESS_CONTROL 0x03
> +
> +#define HDLC_FRAME 0x7E
> +#define HDLC_ESC 0x7D
> +#define HDLC_XOR 0x20
> +
> +#define CONTROL_SVC_START 0x01
> +#define CONTROL_SVC_STOP 0x02
> +
> +/* The maximum number of CPorts supported by Greybus Host Device */
> +#define GB_MAX_CPORTS 32
> +
> +/**
> + * struct gb_beagleplay - BeaglePlay Greybus driver
> + *
> + * @sd: underlying serdev device
> + *
> + * @gb_hd: greybus host device
> + *
> + * @tx_work: hdlc transmit work
> + * @tx_producer_lock: hdlc transmit data producer lock. acquired when appending data to buffer.
> + * @tx_consumer_lock: hdlc transmit data consumer lock. acquired when sending data over uart.
> + * @tx_circ_buf: hdlc transmit circular buffer.
> + * @tx_crc: hdlc transmit crc-ccitt fcs
> + *
> + * @rx_buffer_len: length of receive buffer filled.
> + * @rx_buffer: hdlc frame receive buffer
> + * @rx_in_esc: hdlc rx flag to indicate ESC frame
> + */
> +struct gb_beagleplay {
> +	struct serdev_device *sd;
> +
> +	struct gb_host_device *gb_hd;
> +
> +	struct work_struct tx_work;
> +	spinlock_t tx_producer_lock;
> +	spinlock_t tx_consumer_lock;
> +	struct circ_buf tx_circ_buf;
> +	u16 tx_crc;
> +
> +	u16 rx_buffer_len;
> +	bool rx_in_esc;
> +	u8 rx_buffer[MAX_RX_HDLC];
> +};
> +
> +/**
> + * struct hdlc_payload - Structure to represent part of HDCL frame payload data.
> + *
> + * @len: buffer length in bytes
> + * @buf: payload buffer
> + */
> +struct hdlc_payload {
> +	u16 len;
> +	void *buf;
> +};
> +
> +static void hdlc_rx_greybus_frame(struct gb_beagleplay *bg, u8 *buf, u16 len)
> +{
> +	u16 cport_id;
> +	struct gb_operation_msg_hdr *hdr = (struct gb_operation_msg_hdr *)buf;
> +
> +	memcpy(&cport_id, hdr->pad, sizeof(cport_id));
> +
> +	dev_dbg(&bg->sd->dev, "Greybus Operation %u type %X cport %u status %u received",
> +		hdr->operation_id, hdr->type, cport_id, hdr->result);
> +
> +	greybus_data_rcvd(bg->gb_hd, cport_id, buf, len);
> +}
> +
> +static void hdlc_rx_dbg_frame(const struct gb_beagleplay *bg, const char *buf, u16 len)
> +{
> +	dev_dbg(&bg->sd->dev, "CC1352 Log: %.*s", (int)len, buf);
> +}
> +
> +/**
> + * hdlc_write() - Consume HDLC Buffer.
> + * @bg: beagleplay greybus driver
> + *
> + * Assumes that consumer lock has been acquired.
> + */
> +static void hdlc_write(struct gb_beagleplay *bg)
> +{
> +	int written;
> +	/* Start consuming HDLC data */
> +	int head = smp_load_acquire(&bg->tx_circ_buf.head);
> +	int tail = bg->tx_circ_buf.tail;
> +	int count = CIRC_CNT_TO_END(head, tail, TX_CIRC_BUF_SIZE);
> +	const unsigned char *buf = &bg->tx_circ_buf.buf[tail];
> +
> +	if (count > 0) {
> +		written = serdev_device_write_buf(bg->sd, buf, count);
> +
> +		/* Finish consuming HDLC data */
> +		smp_store_release(&bg->tx_circ_buf.tail, (tail + written) & (TX_CIRC_BUF_SIZE - 1));
> +	}
> +}
> +
> +/**
> + * hdlc_append() - Queue HDLC data for sending.
> + * @bg: beagleplay greybus driver
> + * @value: hdlc byte to transmit
> + *
> + * Assumes that producer lock as been acquired.
> + */
> +static void hdlc_append(struct gb_beagleplay *bg, u8 value)
> +{
> +	int tail, head = bg->tx_circ_buf.head;
> +
> +	while (true) {
> +		tail = READ_ONCE(bg->tx_circ_buf.tail);
> +
> +		if (CIRC_SPACE(head, tail, TX_CIRC_BUF_SIZE) >= 1) {
> +			bg->tx_circ_buf.buf[head] = value;
> +
> +			/* Finish producing HDLC byte */
> +			smp_store_release(&bg->tx_circ_buf.head,
> +					  (head + 1) & (TX_CIRC_BUF_SIZE - 1));
> +			return;
> +		}
> +		dev_warn(&bg->sd->dev, "Tx circ buf full");
> +		usleep_range(3000, 5000);
> +	}
> +}
> +
> +static void hdlc_append_escaped(struct gb_beagleplay *bg, u8 value)
> +{
> +	if (value == HDLC_FRAME || value == HDLC_ESC) {
> +		hdlc_append(bg, HDLC_ESC);
> +		value ^= HDLC_XOR;
> +	}
> +	hdlc_append(bg, value);
> +}
> +
> +static void hdlc_append_tx_frame(struct gb_beagleplay *bg)
> +{
> +	bg->tx_crc = 0xFFFF;
> +	hdlc_append(bg, HDLC_FRAME);
> +}
> +
> +static void hdlc_append_tx_u8(struct gb_beagleplay *bg, u8 value)
> +{
> +	bg->tx_crc = crc_ccitt(bg->tx_crc, &value, 1);
> +	hdlc_append_escaped(bg, value);
> +}
> +
> +static void hdlc_append_tx_buf(struct gb_beagleplay *bg, const u8 *buf, u16 len)
> +{
> +	size_t i;
> +
> +	for (i = 0; i < len; i++)
> +		hdlc_append_tx_u8(bg, buf[i]);
> +}
> +
> +static void hdlc_append_tx_crc(struct gb_beagleplay *bg)
> +{
> +	bg->tx_crc ^= 0xffff;
> +	hdlc_append_escaped(bg, bg->tx_crc & 0xff);
> +	hdlc_append_escaped(bg, (bg->tx_crc >> 8) & 0xff);
> +}
> +
> +static void hdlc_transmit(struct work_struct *work)
> +{
> +	struct gb_beagleplay *bg = container_of(work, struct gb_beagleplay, tx_work);
> +
> +	spin_lock_bh(&bg->tx_consumer_lock);
> +	hdlc_write(bg);
> +	spin_unlock_bh(&bg->tx_consumer_lock);
> +}
> +
> +static void hdlc_tx_frames(struct gb_beagleplay *bg, u8 address, u8 control,
> +			   const struct hdlc_payload payloads[], size_t count)
> +{
> +	size_t i;
> +
> +	spin_lock(&bg->tx_producer_lock);
> +
> +	hdlc_append_tx_frame(bg);
> +	hdlc_append_tx_u8(bg, address);
> +	hdlc_append_tx_u8(bg, control);
> +
> +	for (i = 0; i < count; ++i)
> +		hdlc_append_tx_buf(bg, payloads[i].buf, payloads[i].len);
> +
> +	hdlc_append_tx_crc(bg);
> +	hdlc_append_tx_frame(bg);
> +
> +	spin_unlock(&bg->tx_producer_lock);
> +
> +	schedule_work(&bg->tx_work);
> +}
> +
> +static void hdlc_tx_s_frame_ack(struct gb_beagleplay *bg)
> +{
> +	hdlc_tx_frames(bg, bg->rx_buffer[0], (bg->rx_buffer[1] >> 1) & 0x7, NULL, 0);
> +}
> +
> +static void hdlc_rx_frame(struct gb_beagleplay *bg)
> +{
> +	u16 crc, len;
> +	u8 ctrl, *buf;
> +	u8 address = bg->rx_buffer[0];
> +
> +	crc = crc_ccitt(0xffff, bg->rx_buffer, bg->rx_buffer_len);
> +	if (crc != 0xf0b8) {
> +		dev_warn_ratelimited(&bg->sd->dev, "CRC failed from %02x: 0x%04x", address, crc);
> +		return;
> +	}
> +
> +	ctrl = bg->rx_buffer[1];
> +	buf = &bg->rx_buffer[2];
> +	len = bg->rx_buffer_len - 4;
> +
> +	/* I-Frame, send S-Frame ACK */
> +	if ((ctrl & 1) == 0)
> +		hdlc_tx_s_frame_ack(bg);
> +
> +	switch (address) {
> +	case ADDRESS_DBG:
> +		hdlc_rx_dbg_frame(bg, buf, len);
> +		break;
> +	case ADDRESS_GREYBUS:
> +		hdlc_rx_greybus_frame(bg, buf, len);
> +		break;
> +	default:
> +		dev_warn_ratelimited(&bg->sd->dev, "unknown frame %u", address);
> +	}
> +}
> +
> +static int hdlc_rx(struct gb_beagleplay *bg, const u8 *data, size_t count)
> +{
> +	size_t i;
> +	u8 c;
> +
> +	for (i = 0; i < count; ++i) {
> +		c = data[i];
> +
> +		switch (c) {
> +		case HDLC_FRAME:
> +			if (bg->rx_buffer_len)
> +				hdlc_rx_frame(bg);
> +
> +			bg->rx_buffer_len = 0;
> +			break;
> +		case HDLC_ESC:
> +			bg->rx_in_esc = true;
> +			break;
> +		default:
> +			if (bg->rx_in_esc) {
> +				c ^= 0x20;
> +				bg->rx_in_esc = false;
> +			}
> +
> +			if (bg->rx_buffer_len < MAX_RX_HDLC) {
> +				bg->rx_buffer[bg->rx_buffer_len] = c;
> +				bg->rx_buffer_len++;
> +			} else {
> +				dev_err_ratelimited(&bg->sd->dev, "RX Buffer Overflow");
> +				bg->rx_buffer_len = 0;
> +			}
> +		}
> +	}
> +
> +	return count;
> +}
> +
> +static int hdlc_init(struct gb_beagleplay *bg)
> +{
> +	INIT_WORK(&bg->tx_work, hdlc_transmit);
> +	spin_lock_init(&bg->tx_producer_lock);
> +	spin_lock_init(&bg->tx_consumer_lock);
> +	bg->tx_circ_buf.head = 0;
> +	bg->tx_circ_buf.tail = 0;
> +
> +	bg->tx_circ_buf.buf = devm_kmalloc(&bg->sd->dev, TX_CIRC_BUF_SIZE, GFP_KERNEL);
> +	if (!bg->tx_circ_buf.buf)
> +		return -ENOMEM;
> +
> +	bg->rx_buffer_len = 0;
> +	bg->rx_in_esc = false;
> +
> +	return 0;
> +}
> +
> +static void hdlc_deinit(struct gb_beagleplay *bg)
> +{
> +	flush_work(&bg->tx_work);
> +}
> +
> +static int gb_tty_receive(struct serdev_device *sd, const unsigned char *data, size_t count)
> +{
> +	struct gb_beagleplay *bg = serdev_device_get_drvdata(sd);
> +
> +	return hdlc_rx(bg, data, count);
> +}
> +
> +static void gb_tty_wakeup(struct serdev_device *serdev)
> +{
> +	struct gb_beagleplay *bg = serdev_device_get_drvdata(serdev);
> +
> +	schedule_work(&bg->tx_work);
> +}
> +
> +static struct serdev_device_ops gb_beagleplay_ops = {
> +	.receive_buf = gb_tty_receive,
> +	.write_wakeup = gb_tty_wakeup,
> +};
> +
> +static int gb_message_send(struct gb_host_device *hd, u16 cport, struct gb_message *msg, gfp_t mask)
> +{
> +	struct gb_beagleplay *bg = dev_get_drvdata(&hd->dev);
> +	struct hdlc_payload payloads[2];
> +
> +	dev_dbg(&hd->dev, "Sending greybus message with Operation %u, Type: %X on Cport %u",
> +		msg->header->operation_id, msg->header->type, cport);
> +
> +	if (msg->header->size > RX_HDLC_PAYLOAD)
> +		return dev_err_probe(&hd->dev, -E2BIG, "Greybus message too big");
> +
> +	memcpy(msg->header->pad, &cport, sizeof(cport));
> +
> +	payloads[0].buf = msg->header;
> +	payloads[0].len = sizeof(*msg->header);
> +	payloads[1].buf = msg->payload;
> +	payloads[1].len = msg->payload_size;
> +
> +	hdlc_tx_frames(bg, ADDRESS_GREYBUS, 0x03, payloads, 2);
> +	greybus_message_sent(bg->gb_hd, msg, 0);
> +
> +	return 0;
> +}
> +
> +static void gb_message_cancel(struct gb_message *message)
> +{
> +}
> +

I am not quite sure how to deal with `message_cancel`. The current 
greybus message follow the following trajectory: Linux driver --UART--> 
CC1352 Firmware --6lowpan--> greybus node.

The main method I can currently think to implement this in the Linux 
driver. I can maintain an array containing a canceled greybus message ID 
and a timestamp of when it was added. There are two ways to have a 
message removed from this array:

1. A canceled message is received: Just remove the message from array 
and drop the received message.

2. We have a GC kind of thing which cleans up array members if a set 
timeout has passed since timestamp.


Or maybe I am wrong and the expectation of `message_callback` is 
different from what I tried to solve above?


Sincerely

Ayush Singh

Re: [PATCH v8 2/3] greybus: Add BeaglePlay Linux Driver

[Greg KH]

On Fri, Oct 13, 2023 at 05:11:23PM +0530, Ayush Singh wrote:
> Hello everyone, I would like to get some feedback on the driver patch before
> submitting the new version of this patch series.

I don't want to review a version that I know you are going to resubmit,
as that would waste my time when I should be reviewing patches from
others that they think are complete.

So just update and resend the new series please, no need to ask.

thanks,

greg k-h