Subject: Re: [PATCH v2 3/4] bluetooth: hci_uart: add LL protocol serdev driver support

From: Dan Williams <[email-masked]>
Date: Fri, 07 Apr 2017 12:09:38 -0500

On Fri, 2017-04-07 at 09:35 -0500, Rob Herring wrote:
> Turns out that the LL protocol and the TI-ST are the same thing
> AFAICT.
> The TI-ST adds firmware loading, GPIO control, and shared access for
> NFC, FM radio, etc. For now, we're only implementing what is needed
> for
> BT. This mirrors other drivers like BCM and Intel, but uses the new
> serdev bus.
> 
> The firmware loading is greatly simplified by using existing
> infrastructure to send commands. It may be a bit slower than the
> original code using synchronous functions, but the real bottleneck is
> likely doing firmware load at 115.2kbps.

Is there no way to put the TI-specific stuff into a TI UART module
rather than building it into the generic one?

Dan

> Signed-off-by: Rob Herring <[email-masked]>
> Cc: Marcel Holtmann <[email-masked]>
> Cc: Gustavo Padovan <[email-masked]>
> Cc: Johan Hedberg <[email-masked]>
> Cc: [email-masked]
> ---
> v2:
> - Use IS_ENABLED() to fix module build
> 
>  drivers/bluetooth/hci_ll.c | 261
> ++++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 260 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/bluetooth/hci_ll.c b/drivers/bluetooth/hci_ll.c
> index 02692fe30279..77648adfd5c9 100644
> --- a/drivers/bluetooth/hci_ll.c
> +++ b/drivers/bluetooth/hci_ll.c
> @@ -34,20 +34,23 @@
>  #include <linux/sched.h>
>  #include <linux/types.h>
>  #include <linux/fcntl.h>
> +#include <linux/firmware.h>
>  #include <linux/interrupt.h>
>  #include <linux/ptrace.h>
>  #include <linux/poll.h>
>  
>  #include <linux/slab.h>
> -#include <linux/tty.h>
>  #include <linux/errno.h>
>  #include <linux/string.h>
>  #include <linux/signal.h>
>  #include <linux/ioctl.h>
> +#include <linux/serdev.h>
>  #include <linux/skbuff.h>
> +#include <linux/ti_wilink_st.h>
>  
>  #include <net/bluetooth/bluetooth.h>
>  #include <net/bluetooth/hci_core.h>
> +#include <linux/gpio/consumer.h>
>  
>  #include "hci_uart.h"
>  
> @@ -76,6 +79,12 @@ struct hcill_cmd {
>  	u8 cmd;
>  } __packed;
>  
> +struct ll_device {
> +	struct hci_uart hu;
> +	struct serdev_device *serdev;
> +	struct gpio_desc *enable_gpio;
> +};
> +
>  struct ll_struct {
>  	unsigned long rx_state;
>  	unsigned long rx_count;
> @@ -136,6 +145,9 @@ static int ll_open(struct hci_uart *hu)
>  
>  	hu->priv = ll;
>  
> +	if (hu->serdev)
> +		serdev_device_open(hu->serdev);
> +
>  	return 0;
>  }
>  
> @@ -164,6 +176,13 @@ static int ll_close(struct hci_uart *hu)
>  
>  	kfree_skb(ll->rx_skb);
>  
> +	if (hu->serdev) {
> +		struct ll_device *lldev =
> serdev_device_get_drvdata(hu->serdev);
> +		gpiod_set_value_cansleep(lldev->enable_gpio, 0);
> +
> +		serdev_device_close(hu->serdev);
> +	}
> +
>  	hu->priv = NULL;
>  
>  	kfree(ll);
> @@ -505,9 +524,245 @@ static struct sk_buff *ll_dequeue(struct
> hci_uart *hu)
>  	return skb_dequeue(&ll->txq);
>  }
>  
> +#if IS_ENABLED(CONFIG_SERIAL_DEV_BUS)
> +static int read_local_version(struct hci_dev *hdev)
> +{
> +	int err = 0;
> +	unsigned short version = 0;
> +	struct sk_buff *skb;
> +	struct hci_rp_read_local_version *ver;
> +
> +	skb = __hci_cmd_sync(hdev, HCI_OP_READ_LOCAL_VERSION, 0,
> NULL, HCI_INIT_TIMEOUT);
> +	if (IS_ERR(skb)) {
> +		bt_dev_err(hdev, "Reading TI version information
> failed (%ld)",
> +			   PTR_ERR(skb));
> +		err = PTR_ERR(skb);
> +		goto out;
> +	}
> +	if (skb->len != sizeof(*ver)) {
> +		err = -EILSEQ;
> +		goto out;
> +	}
> +
> +	ver = (struct hci_rp_read_local_version *)skb->data;
> +	if (le16_to_cpu(ver->manufacturer) != 13) {
> +		err = -ENODEV;
> +		goto out;
> +	}
> +
> +	version = le16_to_cpu(ver->lmp_subver);
> +
> +out:
> +	if (err) bt_dev_err(hdev, "Failed to read TI version info:
> %d", err);
> +	kfree_skb(skb);
> +	return err ? err : version;
> +}
> +
> +/**
> + * download_firmware -
> + *	internal function which parses through the .bts firmware
> + *	script file intreprets SEND, DELAY actions only as of now
> + */
> +static int download_firmware(struct ll_device *lldev)
> +{
> +	unsigned short chip, min_ver, maj_ver;
> +	int version, err, len;
> +	unsigned char *ptr, *action_ptr;
> +	unsigned char bts_scr_name[40];	/* 40 char long bts
> scr name? */
> +	const struct firmware *fw;
> +	struct sk_buff *skb;
> +	struct hci_command *cmd;
> +
> +	version = read_local_version(lldev->hu.hdev);
> +	if (version < 0)
> +		return version;
> +
> +	chip = (version & 0x7C00) >> 10;
> +	min_ver = (version & 0x007F);
> +	maj_ver = (version & 0x0380) >> 7;
> +	if (version & 0x8000)
> +		maj_ver |= 0x0008;
> +
> +	snprintf(bts_scr_name, sizeof(bts_scr_name),
> +		 "ti-connectivity/TIInit_%d.%d.%d.bts",
> +		 chip, maj_ver, min_ver);
> +
> +	err = request_firmware(&fw, bts_scr_name, &lldev->serdev-
> >dev);
> +	if (err || !fw->data || !fw->size) {
> +		bt_dev_err(lldev->hu.hdev, "request_firmware
> failed(errno %d) for %s",
> +			   err, bts_scr_name);
> +		return -EINVAL;
> +	}
> +	ptr = (void *)fw->data;
> +	len = fw->size;
> +	/* bts_header to remove out magic number and
> +	 * version
> +	 */
> +	ptr += sizeof(struct bts_header);
> +	len -= sizeof(struct bts_header);
> +
> +	while (len > 0 && ptr) {
> +		bt_dev_dbg(lldev->hu.hdev, " action size %d, type %d
> ",
> +			   ((struct bts_action *)ptr)->size,
> +			   ((struct bts_action *)ptr)->type);
> +
> +		action_ptr = &(((struct bts_action *)ptr)->data[0]);
> +
> +		switch (((struct bts_action *)ptr)->type) {
> +		case ACTION_SEND_COMMAND:	/* action send */
> +			bt_dev_dbg(lldev->hu.hdev, "S");
> +			cmd = (struct hci_command *)action_ptr;
> +			if (cmd->opcode == 0xff36) {
> +				/* ignore remote change
> +				 * baud rate HCI VS command */
> +				bt_dev_warn(lldev->hu.hdev, "change
> remote baud rate command in firmware");
> +				break;
> +			}
> +			if (cmd->prefix != 1)
> +				bt_dev_dbg(lldev->hu.hdev, "command
> type %d\n", cmd->prefix);
> +
> +			skb = __hci_cmd_sync(lldev->hu.hdev, cmd-
> >opcode, cmd->plen, &cmd->speed, HCI_INIT_TIMEOUT);
> +			if (IS_ERR(skb)) {
> +				bt_dev_err(lldev->hu.hdev, "send
> command failed\n");
> +				goto out_rel_fw;
> +			}
> +			kfree_skb(skb);
> +			break;
> +		case ACTION_WAIT_EVENT:  /* wait */
> +			/* no need to wait as command was
> synchronous */
> +			bt_dev_dbg(lldev->hu.hdev, "W");
> +			break;
> +		case ACTION_DELAY:	/* sleep */
> +			bt_dev_info(lldev->hu.hdev, "sleep command
> in scr");
> +			mdelay(((struct bts_action_delay
> *)action_ptr)->msec);
> +			break;
> +		}
> +		len -= (sizeof(struct bts_action) +
> +			((struct bts_action *)ptr)->size);
> +		ptr += sizeof(struct bts_action) +
> +			((struct bts_action *)ptr)->size;
> +	}
> +
> +out_rel_fw:
> +	/* fw download complete */
> +	release_firmware(fw);
> +	return err;
> +}
> +
> +static int ll_setup(struct hci_uart *hu)
> +{
> +	int err, retry = 3;
> +	struct ll_device *lldev;
> +	struct serdev_device *serdev = hu->serdev;
> +	u32 speed;
> +
> +	if (!serdev)
> +		return 0;
> +
> +	lldev = serdev_device_get_drvdata(serdev);
> +
> +	serdev_device_set_flow_control(serdev, true);
> +
> +	do {
> +		/* Configure BT_EN to HIGH state */
> +		gpiod_set_value_cansleep(lldev->enable_gpio, 0);
> +		msleep(5);
> +		gpiod_set_value_cansleep(lldev->enable_gpio, 1);
> +		msleep(100);
> +
> +		err = download_firmware(lldev);
> +		if (!err)
> +			break;
> +
> +		/* Toggle BT_EN and retry */
> +		bt_dev_err(hu->hdev, "download firmware failed,
> retrying...");
> +	} while (retry--);
> +
> +	if (err)
> +		return err;
> +
> +	/* Operational speed if any */
> +	if (hu->oper_speed)
> +		speed = hu->oper_speed;
> +	else if (hu->proto->oper_speed)
> +		speed = hu->proto->oper_speed;
> +	else
> +		speed = 0;
> +
> +	if (speed) {
> +		struct sk_buff *skb = __hci_cmd_sync(hu->hdev,
> 0xff36, sizeof(speed), &speed, HCI_INIT_TIMEOUT);
> +		if (!IS_ERR(skb)) {
> +			kfree_skb(skb);
> +			serdev_device_set_baudrate(serdev, speed);
> +		}
> +	}
> +
> +	return 0;
> +}
> +
> +static const struct hci_uart_proto llp;
> +
> +static int hci_ti_probe(struct serdev_device *serdev)
> +{
> +	struct hci_uart *hu;
> +	struct ll_device *lldev;
> +	u32 max_speed = 3000000;
> +
> +	lldev = devm_kzalloc(&serdev->dev, sizeof(struct ll_device),
> GFP_KERNEL);
> +	if (!lldev)
> +		return -ENOMEM;
> +	hu = &lldev->hu;
> +
> +	serdev_device_set_drvdata(serdev, lldev);
> +	lldev->serdev = hu->serdev = serdev;
> +
> +	lldev->enable_gpio = devm_gpiod_get_optional(&serdev->dev,
> "enable", GPIOD_OUT_LOW);
> +	if (IS_ERR(lldev->enable_gpio))
> +		return PTR_ERR(lldev->enable_gpio);
> +
> +	of_property_read_u32(serdev->dev.of_node, "max-speed",
> &max_speed);
> +	hci_uart_set_speeds(hu, 115200, max_speed);
> +
> +	return hci_uart_register_device(hu, &llp);
> +}
> +
> +static void hci_ti_remove(struct serdev_device *serdev)
> +{
> +	struct ll_device *lldev = serdev_device_get_drvdata(serdev);
> +	struct hci_uart *hu = &lldev->hu;
> +	struct hci_dev *hdev = hu->hdev;
> +
> +	cancel_work_sync(&hu->write_work);
> +
> +	hci_unregister_dev(hdev);
> +	hci_free_dev(hdev);
> +	hu->proto->close(hu);
> +}
> +
> +static const struct of_device_id hci_ti_of_match[] = {
> +	{ .compatible = "ti,wl1831-st" },
> +	{ .compatible = "ti,wl1835-st" },
> +	{ .compatible = "ti,wl1837-st" },
> +	{},
> +};
> +MODULE_DEVICE_TABLE(of, hci_ti_of_match);
> +
> +static struct serdev_device_driver hci_ti_drv = {
> +	.driver		= {
> +		.name	= "hci-ti",
> +		.of_match_table = of_match_ptr(hci_ti_of_match),
> +	},
> +	.probe	= hci_ti_probe,
> +	.remove	= hci_ti_remove,
> +};
> +#else
> +#define ll_setup NULL
> +#endif
> +
>  static const struct hci_uart_proto llp = {
>  	.id		= HCI_UART_LL,
>  	.name		= "LL",
> +	.setup		= ll_setup,
>  	.open		= ll_open,
>  	.close		= ll_close,
>  	.recv		= ll_recv,
> @@ -518,10 +773,14 @@ static const struct hci_uart_proto llp = {
>  
>  int __init ll_init(void)
>  {
> +	serdev_device_driver_register(&hci_ti_drv);
> +
>  	return hci_uart_register_proto(&llp);
>  }
>  
>  int __exit ll_deinit(void)
>  {
> +	serdev_device_driver_unregister(&hci_ti_drv);
> +
>  	return hci_uart_unregister_proto(&llp);
>  }