Re: [PATCH 2/2] can: spi: hi311x: Add Holt HI-311x CAN driver

[Marc Kleine-Budde]

On 11/14/2016 06:55 PM, Akshay Bhat wrote:
> This patch adds support for the Holt HI-311x CAN controller. The HI311x
> CAN controller is capable of transmitting and receiving standard data
> frames, extended data frames and remote frames. The HI311x interfaces
> with the host over SPI.

Don't use uint8_t and similar in the kernel, please use u8 instead.

> 
> Datasheet: www.holtic.com/documents/371-hi-3110_v-rev-jpdf.do
> 
> Signed-off-by: Akshay Bhat <nodeax@xxxxxxxxx>
> ---
>  drivers/net/can/spi/Kconfig  |    6 +
>  drivers/net/can/spi/Makefile |    1 +
>  drivers/net/can/spi/hi311x.c | 1071 ++++++++++++++++++++++++++++++++++++++++++
>  3 files changed, 1078 insertions(+)
>  create mode 100644 drivers/net/can/spi/hi311x.c
> 
> diff --git a/drivers/net/can/spi/Kconfig b/drivers/net/can/spi/Kconfig
> index 148cae5..9eb1bb1 100644
> --- a/drivers/net/can/spi/Kconfig
> +++ b/drivers/net/can/spi/Kconfig
> @@ -7,4 +7,10 @@ config CAN_MCP251X
>  	---help---
>  	  Driver for the Microchip MCP251x SPI CAN controllers.
>  
> +config CAN_HI311X
> +	tristate "Holt HI311x SPI CAN controllers"
> +	depends on CAN_DEV && SPI && HAS_DMA
> +	---help---
> +	  Driver for the Holt HI311x SPI CAN controllers.
> +
>  endmenu
> diff --git a/drivers/net/can/spi/Makefile b/drivers/net/can/spi/Makefile
> index 0e86040..eac7c3a 100644
> --- a/drivers/net/can/spi/Makefile
> +++ b/drivers/net/can/spi/Makefile
> @@ -4,3 +4,4 @@
>  
>  
>  obj-$(CONFIG_CAN_MCP251X)	+= mcp251x.o
> +obj-$(CONFIG_CAN_HI311X)	+= hi311x.o

Please keep sorted alphabetically. Same for the Kconfig.

> diff --git a/drivers/net/can/spi/hi311x.c b/drivers/net/can/spi/hi311x.c
> new file mode 100644
> index 0000000..1020166
> --- /dev/null
> +++ b/drivers/net/can/spi/hi311x.c
> @@ -0,0 +1,1071 @@
> +/* CAN bus driver for Holt HI3110 CAN Controller with SPI Interface
> + *
> + * Based on Microchip 251x CAN Controller (mcp251x) Linux kernel driver

You might want to add the copyright of the mcp authors.

> + *
> + * Copyright(C) Timesys Corporation 2016
> + *
> + * This program is free software; you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License version 2 as
> + * published by the Free Software Foundation.
> + */
> +
> +#include <linux/can/core.h>
> +#include <linux/can/dev.h>
> +#include <linux/can/led.h>
> +#include <linux/clk.h>
> +#include <linux/completion.h>
> +#include <linux/delay.h>
> +#include <linux/device.h>
> +#include <linux/dma-mapping.h>
> +#include <linux/freezer.h>
> +#include <linux/interrupt.h>
> +#include <linux/io.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/netdevice.h>
> +#include <linux/of.h>
> +#include <linux/of_device.h>
> +#include <linux/platform_device.h>
> +#include <linux/regulator/consumer.h>
> +#include <linux/slab.h>
> +#include <linux/spi/spi.h>
> +#include <linux/uaccess.h>
> +

Please use just a single space after each macro.

                              VVVVVVVV
> +#define HI3110_MASTER_RESET        0x56
> +#define HI3110_READ_CTRL0          0xD2
> +#define HI3110_READ_CTRL1          0xD4
> +#define HI3110_READ_STATF          0xE2
> +#define HI3110_WRITE_CTRL0         0x14
> +#define HI3110_WRITE_CTRL1         0x16
> +#define HI3110_WRITE_INTE          0x1C
> +#define HI3110_WRITE_BTR0          0x18
> +#define HI3110_WRITE_BTR1          0x1A
> +#define HI3110_READ_BTR0           0xD6
> +#define HI3110_READ_BTR1           0xD8
> +#define HI3110_READ_INTF           0xDE
> +#define HI3110_READ_ERR            0xDC
> +#define HI3110_READ_FIFO_WOTIME    0x48
> +#define HI3110_WRITE_FIFO          0x12
> +#define HI3110_READ_MESSTAT        0xDA
> +#define HI3110_READ_TEC            0xEC
> +
> +#define HI3110_CTRL0_MODE_MASK     (7 << 5)
> +#define HI3110_CTRL0_NORMAL_MODE   (0 << 5)
> +#define HI3110_CTRL0_LOOPBACK_MODE (1 << 5)
> +#define HI3110_CTRL0_MONITOR_MODE  (2 << 5)
> +#define HI3110_CTRL0_SLEEP_MODE    (3 << 5)
> +#define HI3110_CTRL0_INIT_MODE     (4 << 5)
> +
> +#define HI3110_CTRL1_TXEN          BIT(7)
> +
> +#define HI3110_INT_RXTMP           BIT(7)
> +#define HI3110_INT_RXFIFO          BIT(6)
> +#define HI3110_INT_TXCPLT          BIT(5)
> +#define HI3110_INT_BUSERR          BIT(4)
> +#define HI3110_INT_MCHG            BIT(3)
> +#define HI3110_INT_WAKEUP          BIT(2)
> +#define HI3110_INT_F1MESS          BIT(1)
> +#define HI3110_INT_F0MESS          BIT(0)
> +
> +#define HI3110_ERR_BUSOFF          BIT(7)
> +#define HI3110_ERR_TXERRP          BIT(6)
> +#define HI3110_ERR_RXERRP          BIT(5)
> +#define HI3110_ERR_BITERR          BIT(4)
> +#define HI3110_ERR_FRMERR          BIT(3)
> +#define HI3110_ERR_CRCERR          BIT(2)
> +#define HI3110_ERR_ACKERR          BIT(1)
> +#define HI3110_ERR_STUFERR         BIT(0)
> +#define HI3110_ERR_PROTOCOL_MASK   (0x1F)
> +
> +#define HI3110_STAT_RXFMTY         BIT(1)
> +
> +#define HI3110_BTR0_SJW_SHIFT      6
> +#define HI3110_BTR0_BRP_SHIFT      0
> +
> +#define HI3110_BTR1_SAMP_3PERBIT   (1 << 7)
> +#define HI3110_BTR1_SAMP_1PERBIT   (0 << 7)
> +#define HI3110_BTR1_TSEG2_SHIFT    4
> +#define HI3110_BTR1_TSEG1_SHIFT    0
> +
> +#define HI3110_FIFO_WOTIME_TAG_OFF 0
> +#define HI3110_FIFO_WOTIME_ID_OFF  1
> +#define HI3110_FIFO_WOTIME_DLC_OFF 5
> +#define HI3110_FIFO_WOTIME_DAT_OFF 6
> +
> +#define HI3110_FIFO_WOTIME_TAG_IDE BIT(7)
> +#define HI3110_FIFO_WOTIME_ID_RTR  BIT(0)
> +
> +#define HI3110_FIFO_TAG_OFF        0
> +#define HI3110_FIFO_ID_OFF         1
> +#define HI3110_FIFO_STD_DLC_OFF    3
> +#define HI3110_FIFO_STD_DATA_OFF   4
> +#define HI3110_FIFO_EXT_DLC_OFF    5
> +#define HI3110_FIFO_EXT_DATA_OFF   6
> +

Please add the already used HI3110_ namespace to these defines, too.

> +#define CAN_FRAME_MAX_DATA_LEN 8
> +#define RX_BUF_LEN             15
> +#define TX_STD_BUF_LEN         12
> +#define TX_EXT_BUF_LEN         14
> +#define CAN_FRAME_MAX_BITS     128
> +
> +#define TX_ECHO_SKB_MAX	1
> +
> +#define HI3110_OST_DELAY_MS (10)
> +
> +#define DEVICE_NAME "hi3110"
> +
> +static int hi3110_enable_dma = 1; /* Enable SPI DMA. Default: 1 (On) */
> +module_param(hi3110_enable_dma, int, 0444);
> +MODULE_PARM_DESC(hi3110_enable_dma, "Enable SPI DMA. Default: 1 (On)");
> +
> +static const struct can_bittiming_const hi3110_bittiming_const = {
> +	.name = DEVICE_NAME,
> +	.tseg1_min = 2,
> +	.tseg1_max = 16,
> +	.tseg2_min = 2,
> +	.tseg2_max = 8,
> +	.sjw_max = 4,
> +	.brp_min = 1,
> +	.brp_max = 64,
> +	.brp_inc = 1,
> +};
> +
> +enum hi3110_model {
> +	CAN_HI3110_HI3110	= 0x3110,
                         ^^^^^^^
single space here, too
> +};
> +
> +struct hi3110_priv {
> +	struct can_priv	   can;
                       ^^^^
here too
> +	struct net_device *net;
> +	struct spi_device *spi;
> +	enum hi3110_model model;
> +
> +	struct mutex hi3110_lock; /* SPI device lock */
> +
> +	u8 *spi_tx_buf;
> +	u8 *spi_rx_buf;
> +	dma_addr_t spi_tx_dma;
> +	dma_addr_t spi_rx_dma;
> +
> +	struct sk_buff *tx_skb;
> +	int tx_len;
> +
> +	struct workqueue_struct *wq;
> +	struct work_struct tx_work;
> +	struct work_struct restart_work;
> +
> +	int force_quit;
> +	int after_suspend;

Please add the already used HI3110_ namespace to these defines, too.

> +#define AFTER_SUSPEND_UP 1
> +#define AFTER_SUSPEND_DOWN 2
> +#define AFTER_SUSPEND_POWER 4
> +#define AFTER_SUSPEND_RESTART 8

> +	int restart_tx;
> +	struct regulator *power;
> +	struct regulator *transceiver;
> +	struct clk *clk;
> +};
> +
> +static void hi3110_clean(struct net_device *net)
> +{
> +	struct hi3110_priv *priv = netdev_priv(net);
> +
> +	if (priv->tx_skb || priv->tx_len)
> +		net->stats.tx_errors++;
> +	if (priv->tx_skb)
> +		dev_kfree_skb(priv->tx_skb);
> +	if (priv->tx_len)
> +		can_free_echo_skb(priv->net, 0);
> +	priv->tx_skb = NULL;
> +	priv->tx_len = 0;
> +}
> +
> +/* Note about handling of error return of hi3110_spi_trans: accessing
> + * registers via SPI is not really different conceptually than using
> + * normal I/O assembler instructions, although it's much more
> + * complicated from a practical POV. So it's not advisable to always
> + * check the return value of this function. Imagine that every
> + * read{b,l}, write{b,l} and friends would be bracketed in "if ( < 0)
> + * error();", it would be a great mess (well there are some situation
> + * when exception handling C++ like could be useful after all). So we
> + * just check that transfers are OK at the beginning of our
> + * conversation with the chip and to avoid doing really nasty things
> + * (like injecting bogus packets in the network stack).
> + */
> +static int hi3110_spi_trans(struct spi_device *spi, int len)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +	struct spi_transfer t = {
> +		.tx_buf = priv->spi_tx_buf,
> +		.rx_buf = priv->spi_rx_buf,
> +		.len = len,
> +		.cs_change = 0,
> +	};
> +	struct spi_message m;
> +	int ret;
> +
> +	spi_message_init(&m);
> +
> +	if (hi3110_enable_dma) {
> +		t.tx_dma = priv->spi_tx_dma;
> +		t.rx_dma = priv->spi_rx_dma;
> +		m.is_dma_mapped = 1;
> +	}
> +
> +	spi_message_add_tail(&t, &m);
> +
> +	ret = spi_sync(spi, &m);
> +
> +	if (ret)
> +		dev_err(&spi->dev, "spi transfer failed: ret = %d\n", ret);
> +	return ret;
> +}
> +
> +static u8 hi3110_cmd(struct spi_device *spi, uint8_t command)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +
> +	priv->spi_tx_buf[0] = command;
> +	dev_dbg(&spi->dev, "hi3110_cmd: %02X\n", command);
> +
> +	return hi3110_spi_trans(spi, 1);
> +}
> +
> +static u8 hi3110_read(struct spi_device *spi, uint8_t command)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +	u8 val = 0;
> +
> +	priv->spi_tx_buf[0] = command;
> +	hi3110_spi_trans(spi, 2);
> +	val = priv->spi_rx_buf[1];
> +	dev_dbg(&spi->dev, "hi3110_read: %02X, %02X\n", command, val);
> +
> +	return val;
> +}
> +
> +static void hi3110_write(struct spi_device *spi, u8 reg, uint8_t val)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +
> +	priv->spi_tx_buf[0] = reg;
> +	priv->spi_tx_buf[1] = val;
> +	dev_dbg(&spi->dev, "hi3110_write: %02X, %02X\n", reg, val);
> +
> +	hi3110_spi_trans(spi, 2);
> +}
> +
> +static void hi3110_hw_tx_frame(struct spi_device *spi, u8 *buf, int len)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +
> +	priv->spi_tx_buf[0] = HI3110_WRITE_FIFO;
> +	memcpy(priv->spi_tx_buf + 1, buf, len);
> +	hi3110_spi_trans(spi, len + 1);
> +}
> +
> +static void hi3110_hw_tx(struct spi_device *spi, struct can_frame *frame)
> +{
> +	u8 buf[TX_EXT_BUF_LEN];
> +
> +	buf[HI3110_FIFO_TAG_OFF] = 0;
> +
> +	if (frame->can_id & CAN_EFF_FLAG) {
> +		/* Extended frame */
> +		buf[HI3110_FIFO_ID_OFF] = (frame->can_id & CAN_EFF_MASK) >> 21;
> +		buf[HI3110_FIFO_ID_OFF + 1] =
> +			((((frame->can_id & CAN_EFF_MASK) >> 18) & 0x07) << 5) |

Why do you first shift down then up?

> +			0x18 | /* Recessive SRR and IDE */

Can you add a define for the 0x18?

> +			(((frame->can_id & CAN_EFF_MASK) >> 15) & 0x07);
> +		buf[HI3110_FIFO_ID_OFF + 2] =
> +			(frame->can_id & CAN_EFF_MASK) >> 7;
> +		buf[HI3110_FIFO_ID_OFF + 3] =
> +			((frame->can_id & CAN_EFF_MASK) << 1) |
> +			((frame->can_id & CAN_RTR_FLAG) ? 1 : 0);
> +
> +		buf[HI3110_FIFO_EXT_DLC_OFF] = frame->can_dlc;
> +
> +		memcpy(buf + HI3110_FIFO_EXT_DATA_OFF,
> +		       frame->data, frame->can_dlc);
> +
> +		hi3110_hw_tx_frame(spi, buf, TX_EXT_BUF_LEN -
> +				   (CAN_FRAME_MAX_DATA_LEN - frame->can_dlc));
> +	} else {
> +		/* Standard frame */
> +		buf[HI3110_FIFO_ID_OFF] =   (frame->can_id & CAN_SFF_MASK) >> 3;
> +		buf[HI3110_FIFO_ID_OFF + 1] =
> +			((frame->can_id & CAN_SFF_MASK) << 5) |
> +			((frame->can_id & CAN_RTR_FLAG) ? (1 << 4) : 0);
> +
> +		buf[HI3110_FIFO_STD_DLC_OFF] = frame->can_dlc;
> +
> +		memcpy(buf + HI3110_FIFO_STD_DATA_OFF,
> +		       frame->data, frame->can_dlc);
> +
> +		hi3110_hw_tx_frame(spi, buf, TX_STD_BUF_LEN -
> +				   (CAN_FRAME_MAX_DATA_LEN - frame->can_dlc));
> +	}
> +}
> +
> +static void hi3110_hw_rx_frame(struct spi_device *spi, u8 *buf)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +
> +	priv->spi_tx_buf[0] = HI3110_READ_FIFO_WOTIME;
> +	hi3110_spi_trans(spi, RX_BUF_LEN);
> +	memcpy(buf, priv->spi_rx_buf + 1, RX_BUF_LEN - 1);
> +}
> +
> +static void hi3110_hw_rx(struct spi_device *spi)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +	struct sk_buff *skb;
> +	struct can_frame *frame;
> +	u8 buf[RX_BUF_LEN - 1];
> +
> +	skb = alloc_can_skb(priv->net, &frame);
> +	if (!skb) {
> +		dev_err(&spi->dev, "cannot allocate RX skb\n");
> +		priv->net->stats.rx_dropped++;
> +		return;
> +	}
> +
> +	hi3110_hw_rx_frame(spi, buf);
> +	if (buf[HI3110_FIFO_WOTIME_TAG_OFF] & HI3110_FIFO_WOTIME_TAG_IDE) {
> +		/* IDE is recessive (1), indicating extended 29-bit frame */
> +		frame->can_id = CAN_EFF_FLAG;
> +		frame->can_id |=
> +		 (buf[HI3110_FIFO_WOTIME_ID_OFF] << 21) |
> +		 (((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0xE0) >> 5) << 18) |
> +		 ((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0x07) << 15) |
> +		 (buf[HI3110_FIFO_WOTIME_ID_OFF + 2] << 7) |
> +		 (buf[HI3110_FIFO_WOTIME_ID_OFF + 3] >> 1);
> +	} else {
> +		/* IDE is dominant (0), frame indicating standard 11-bit */
> +		frame->can_id =
> +			(buf[HI3110_FIFO_WOTIME_ID_OFF] << 3) |
> +			((buf[HI3110_FIFO_WOTIME_ID_OFF + 1] & 0xE0) >> 5);
> +	}
> +
> +	if (buf[HI3110_FIFO_WOTIME_ID_OFF + 3] & HI3110_FIFO_WOTIME_ID_RTR) {
> +		/* RTR is recessive (1), indicating remote request frame */
> +		frame->can_id |= CAN_RTR_FLAG;
> +	}
> +
> +	/* Data length */
> +	frame->can_dlc = get_can_dlc(buf[HI3110_FIFO_WOTIME_DLC_OFF] & 0x0F);
> +	memcpy(frame->data, buf + HI3110_FIFO_WOTIME_DAT_OFF, frame->can_dlc);
> +
> +	priv->net->stats.rx_packets++;
> +	priv->net->stats.rx_bytes += frame->can_dlc;
> +
> +	can_led_event(priv->net, CAN_LED_EVENT_RX);
> +
> +	netif_rx_ni(skb);
> +}
> +
> +static void hi3110_hw_sleep(struct spi_device *spi)
> +{
> +	hi3110_write(spi, HI3110_WRITE_CTRL0, HI3110_CTRL0_SLEEP_MODE);
> +}
> +
> +static netdev_tx_t hi3110_hard_start_xmit(struct sk_buff *skb,
> +					  struct net_device *net)
> +{
> +	struct hi3110_priv *priv = netdev_priv(net);
> +	struct spi_device *spi = priv->spi;
> +
> +	if (priv->tx_skb || priv->tx_len) {
> +		dev_warn(&spi->dev, "hard_xmit called while tx busy\n");
> +		return NETDEV_TX_BUSY;
> +	}
> +
> +	if (can_dropped_invalid_skb(net, skb))
> +		return NETDEV_TX_OK;
> +
> +	netif_stop_queue(net);
> +	priv->tx_skb = skb;
> +	queue_work(priv->wq, &priv->tx_work);
> +
> +	return NETDEV_TX_OK;
> +}
> +
> +static int hi3110_do_set_mode(struct net_device *net, enum can_mode mode)
> +{
> +	struct hi3110_priv *priv = netdev_priv(net);
> +
> +	switch (mode) {
> +	case CAN_MODE_START:
> +		hi3110_clean(net);
> +		/* We have to delay work since SPI I/O may sleep */
> +		priv->can.state = CAN_STATE_ERROR_ACTIVE;
> +		priv->restart_tx = 1;
> +		if (priv->can.restart_ms == 0)
> +			priv->after_suspend = AFTER_SUSPEND_RESTART;
> +		queue_work(priv->wq, &priv->restart_work);
> +		break;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +
> +	return 0;
> +}
> +
> +static int hi3110_set_normal_mode(struct spi_device *spi)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +	u8 reg;
> +
> +	hi3110_write(spi, HI3110_WRITE_INTE, HI3110_INT_BUSERR |
> +		     HI3110_INT_RXFIFO | HI3110_INT_TXCPLT);
> +
> +	/* Enable TX */
> +	hi3110_write(spi, HI3110_WRITE_CTRL1, HI3110_CTRL1_TXEN);
> +
> +	if (priv->can.ctrlmode & CAN_CTRLMODE_LOOPBACK) {
> +		/* Put device into loopback mode */
> +		hi3110_write(spi, HI3110_WRITE_CTRL0,
> +			     HI3110_CTRL0_LOOPBACK_MODE);
> +	} else if (priv->can.ctrlmode & CAN_CTRLMODE_LISTENONLY) {
> +		/* Put device into listen-only mode */
> +		hi3110_write(spi, HI3110_WRITE_CTRL0,
> +			     HI3110_CTRL0_MONITOR_MODE);
> +	} else {
> +		/* Put device into normal mode */
> +		hi3110_write(spi, HI3110_WRITE_CTRL0,
> +			     HI3110_CTRL0_NORMAL_MODE);
> +
> +		/* Wait for the device to enter normal mode */
> +		mdelay(HI3110_OST_DELAY_MS);
> +		reg = hi3110_read(spi, HI3110_READ_CTRL0);
> +		if ((reg & HI3110_CTRL0_MODE_MASK) != HI3110_CTRL0_NORMAL_MODE)
> +			return -EBUSY;
> +	}
> +	priv->can.state = CAN_STATE_ERROR_ACTIVE;
> +	return 0;
> +}
> +
> +static int hi3110_do_set_bittiming(struct net_device *net)
> +{
> +	struct hi3110_priv *priv = netdev_priv(net);
> +	struct can_bittiming *bt = &priv->can.bittiming;
> +	struct spi_device *spi = priv->spi;
> +
> +	hi3110_write(spi, HI3110_WRITE_BTR0,
> +		     ((bt->sjw - 1) << HI3110_BTR0_SJW_SHIFT) |
> +		     ((bt->brp - 1) << HI3110_BTR0_BRP_SHIFT));
> +
> +	hi3110_write(spi, HI3110_WRITE_BTR1,
> +		     (priv->can.ctrlmode &
> +		     CAN_CTRLMODE_3_SAMPLES ?
> +		     HI3110_BTR1_SAMP_3PERBIT : HI3110_BTR1_SAMP_1PERBIT) |
> +		     ((bt->phase_seg1 + bt->prop_seg - 1)
> +		     << HI3110_BTR1_TSEG1_SHIFT) |
> +		     ((bt->phase_seg2 - 1) << HI3110_BTR1_TSEG2_SHIFT));
> +
> +	dev_dbg(&spi->dev, "BT: 0x%02x 0x%02x\n",
> +		hi3110_read(spi, HI3110_READ_BTR0),
> +		hi3110_read(spi, HI3110_READ_BTR1));
> +
> +	return 0;
> +}
> +
> +static int hi3110_setup(struct net_device *net, struct hi3110_priv *priv,
> +			struct spi_device *spi)

onlt the first parameter is used.

> +{
> +	hi3110_do_set_bittiming(net);
> +	return 0;
> +}
> +
> +static int hi3110_hw_reset(struct spi_device *spi)
> +{
> +	u8 reg;
> +	int ret;
> +
> +	/* Wait for oscillator startup timer after power up */
> +	mdelay(HI3110_OST_DELAY_MS);
> +
> +	ret = hi3110_cmd(spi, HI3110_MASTER_RESET);
> +	if (ret)
> +		return ret;
> +
> +	/* Wait for oscillator startup timer after reset */
> +	mdelay(HI3110_OST_DELAY_MS);
> +
> +	reg = hi3110_read(spi, HI3110_READ_CTRL0);
> +	if ((reg & HI3110_CTRL0_MODE_MASK) != HI3110_CTRL0_INIT_MODE)
> +		return -ENODEV;
> +
> +	/* As per the datasheet it appears the error flags are
> +	 * not cleared on reset. Explicitly clear them by performing a read
> +	 */
> +	hi3110_read(spi, HI3110_READ_ERR);
> +
> +	return 0;
> +}
> +
> +static int hi3110_hw_probe(struct spi_device *spi)
> +{
> +	u8 statf;
> +
> +	hi3110_hw_reset(spi);
> +
> +	/* Confirm correct operation by checking against reset values
> +	 * in datasheet
> +	 */
> +	statf = hi3110_read(spi, HI3110_READ_STATF);
> +
> +	dev_dbg(&spi->dev, "statf: %02X\n", statf);
> +
> +	if (statf != 0x82)
> +		return -ENODEV;
> +
> +	return 0;
> +}
> +
> +static int hi3110_power_enable(struct regulator *reg, int enable)
> +{
> +	if (IS_ERR_OR_NULL(reg))
> +		return 0;
> +
> +	if (enable)
> +		return regulator_enable(reg);
> +	else
> +		return regulator_disable(reg);
> +}
> +
> +static void hi3110_open_clean(struct net_device *net)
> +{
> +	struct hi3110_priv *priv = netdev_priv(net);
> +	struct spi_device *spi = priv->spi;
> +
> +	free_irq(spi->irq, priv);
> +	hi3110_hw_sleep(spi);
> +	hi3110_power_enable(priv->transceiver, 0);
> +	close_candev(net);
> +}
> +
> +static int hi3110_stop(struct net_device *net)
> +{
> +	struct hi3110_priv *priv = netdev_priv(net);
> +	struct spi_device *spi = priv->spi;
> +
> +	close_candev(net);
> +
> +	priv->force_quit = 1;
> +	free_irq(spi->irq, priv);
> +	destroy_workqueue(priv->wq);
> +	priv->wq = NULL;
> +
> +	mutex_lock(&priv->hi3110_lock);
> +
> +	/* Disable transmit, interrupts and clear flags */
> +	hi3110_write(spi, HI3110_WRITE_CTRL1, 0x0);
> +	hi3110_write(spi, HI3110_WRITE_INTE, 0x0);
> +	hi3110_read(spi, HI3110_READ_INTF);
> +
> +	hi3110_clean(net);
> +
> +	hi3110_hw_sleep(spi);
> +
> +	hi3110_power_enable(priv->transceiver, 0);
> +
> +	priv->can.state = CAN_STATE_STOPPED;
> +
> +	mutex_unlock(&priv->hi3110_lock);
> +
> +	can_led_event(net, CAN_LED_EVENT_STOP);
> +
> +	return 0;
> +}
> +
> +static void hi3110_error_skb(struct net_device *net, int can_id,
> +			     int data1, int data2)
> +{
> +	struct sk_buff *skb;
> +	struct can_frame *frame;
> +
> +	skb = alloc_can_err_skb(net, &frame);
> +	if (skb) {
> +		frame->can_id |= can_id;
> +		frame->data[1] = data1;
> +		frame->data[2] = data2;
> +		netif_rx_ni(skb);
> +	} else {
> +		netdev_err(net, "cannot allocate error skb\n");
> +	}
> +}
> +
> +static void hi3110_tx_work_handler(struct work_struct *ws)
> +{
> +	struct hi3110_priv *priv = container_of(ws, struct hi3110_priv,
> +						 tx_work);
> +	struct spi_device *spi = priv->spi;
> +	struct net_device *net = priv->net;
> +	struct can_frame *frame;
> +
> +	mutex_lock(&priv->hi3110_lock);
> +	if (priv->tx_skb) {
> +		if (priv->can.state == CAN_STATE_BUS_OFF) {
> +			hi3110_clean(net);
> +		} else {
> +			frame = (struct can_frame *)priv->tx_skb->data;
> +
> +			if (frame->can_dlc > CAN_FRAME_MAX_DATA_LEN)
> +				frame->can_dlc = CAN_FRAME_MAX_DATA_LEN;

this has already been checked

> +			hi3110_hw_tx(spi, frame);
> +			priv->tx_len = 1 + frame->can_dlc;
> +			can_put_echo_skb(priv->tx_skb, net, 0);
> +			priv->tx_skb = NULL;
> +		}
> +	}
> +	mutex_unlock(&priv->hi3110_lock);
> +}
> +
> +static void hi3110_restart_work_handler(struct work_struct *ws)
> +{
> +	struct hi3110_priv *priv = container_of(ws, struct hi3110_priv,
> +						 restart_work);
> +	struct spi_device *spi = priv->spi;
> +	struct net_device *net = priv->net;
> +
> +	mutex_lock(&priv->hi3110_lock);
> +	if (priv->after_suspend) {
> +		hi3110_hw_reset(spi);
> +		hi3110_setup(net, priv, spi);
> +		if (priv->after_suspend & AFTER_SUSPEND_RESTART) {
> +			hi3110_set_normal_mode(spi);
> +		} else if (priv->after_suspend & AFTER_SUSPEND_UP) {
> +			netif_device_attach(net);
> +			hi3110_clean(net);
> +			hi3110_set_normal_mode(spi);
> +			netif_wake_queue(net);
> +		} else {
> +			hi3110_hw_sleep(spi);
> +		}
> +		priv->after_suspend = 0;
> +		priv->force_quit = 0;
> +	}
> +
> +	if (priv->restart_tx) {
> +		priv->restart_tx = 0;
> +		hi3110_clean(net);
> +		netif_wake_queue(net);
> +		hi3110_error_skb(net, CAN_ERR_RESTARTED, 0, 0);
> +	}
> +	mutex_unlock(&priv->hi3110_lock);
> +}
> +
> +static irqreturn_t hi3110_can_ist(int irq, void *dev_id)
> +{
> +	struct hi3110_priv *priv = dev_id;
> +	struct spi_device *spi = priv->spi;
> +	struct net_device *net = priv->net;
> +
> +	mutex_lock(&priv->hi3110_lock);
> +
> +	while (!priv->force_quit) {
> +		enum can_state new_state;
> +		u8 intf;
> +		u8 eflag;
> +		int can_id = 0, data1 = 0, data2 = 0;
> +
> +		while (!(HI3110_STAT_RXFMTY &
> +			hi3110_read(spi, HI3110_READ_STATF))) {
> +			hi3110_hw_rx(spi);
> +		};
> +
> +		intf = hi3110_read(spi, HI3110_READ_INTF);
> +		eflag = hi3110_read(spi, HI3110_READ_ERR);

does the hardware supports multiple reads with a single transfer? If so
make use of it, for performance reasons.

> +		/* Update can state */
> +		if (eflag & HI3110_ERR_BUSOFF) {
> +			new_state = CAN_STATE_BUS_OFF;
> +			can_id |= CAN_ERR_BUSOFF;
> +		} else if (eflag & HI3110_ERR_TXERRP) {
> +			new_state = CAN_STATE_ERROR_PASSIVE;
> +			can_id |= CAN_ERR_CRTL;
> +			data1 |= CAN_ERR_CRTL_TX_PASSIVE;
> +		} else if (eflag & HI3110_ERR_RXERRP) {
> +			new_state = CAN_STATE_ERROR_PASSIVE;
> +			can_id |= CAN_ERR_CRTL;
> +			data1 |= CAN_ERR_CRTL_RX_PASSIVE;
> +		} else {
> +			new_state = CAN_STATE_ERROR_ACTIVE;
> +		}
> +
> +		/* Check for protocol errors */
> +		if (eflag & HI3110_ERR_PROTOCOL_MASK) {
> +			can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR;
> +			priv->can.can_stats.bus_error++;
> +			priv->net->stats.rx_errors++;
> +			if (eflag & HI3110_ERR_BITERR)
> +				data2 |= CAN_ERR_PROT_BIT;
> +			else if (eflag & HI3110_ERR_FRMERR)
> +				data2 |= CAN_ERR_PROT_FORM;
> +			else if (eflag & HI3110_ERR_STUFERR)
> +				data2 |= CAN_ERR_PROT_STUFF;
> +			else
> +				data2 |= CAN_ERR_PROT_UNSPEC;
> +		}
> +
> +		/* Update can state statistics */
> +		switch (priv->can.state) {
> +		case CAN_STATE_ERROR_ACTIVE:
> +			if (new_state >= CAN_STATE_ERROR_WARNING &&
> +			    new_state <= CAN_STATE_BUS_OFF)
> +				priv->can.can_stats.error_warning++;
> +		/* fallthrough */
> +		case CAN_STATE_ERROR_WARNING:
> +			if (new_state >= CAN_STATE_ERROR_PASSIVE &&
> +			    new_state <= CAN_STATE_BUS_OFF)
> +				priv->can.can_stats.error_passive++;
> +			break;
> +		default:
> +			break;
> +		}
> +		priv->can.state = new_state;
> +
> +		if (intf & HI3110_INT_BUSERR) {
> +			/* Note: HI3110 Does report overflow errors */
> +			hi3110_error_skb(net, can_id, data1, data2);
> +		}
> +
> +		if (priv->can.state == CAN_STATE_BUS_OFF) {
> +			if (priv->can.restart_ms == 0) {
> +				priv->force_quit = 1;
> +				priv->can.can_stats.bus_off++;
> +				can_bus_off(net);
> +				hi3110_hw_sleep(spi);
> +				break;
> +			}
> +		}
> +
> +		if (intf == 0)
> +			break;
> +
> +		if (intf & HI3110_INT_TXCPLT) {
> +			net->stats.tx_packets++;
> +			net->stats.tx_bytes += priv->tx_len - 1;
> +			can_led_event(net, CAN_LED_EVENT_TX);
> +			if (priv->tx_len) {
> +				can_get_echo_skb(net, 0);
> +				priv->tx_len = 0;
> +			}
> +			netif_wake_queue(net);
> +		}
> +	}
> +	mutex_unlock(&priv->hi3110_lock);
> +	return IRQ_HANDLED;
> +}
> +
> +static int hi3110_open(struct net_device *net)
> +{
> +	struct hi3110_priv *priv = netdev_priv(net);
> +	struct spi_device *spi = priv->spi;
> +	unsigned long flags = IRQF_ONESHOT | IRQF_TRIGGER_RISING;
> +	int ret;
> +
> +	ret = open_candev(net);
> +	if (ret) {
> +		dev_err(&spi->dev, "unable to set initial baudrate!\n");
> +		return ret;
> +	}
> +
> +	mutex_lock(&priv->hi3110_lock);
> +	hi3110_power_enable(priv->transceiver, 1);
> +
> +	priv->force_quit = 0;
> +	priv->tx_skb = NULL;
> +	priv->tx_len = 0;
> +
> +	ret = request_threaded_irq(spi->irq, NULL, hi3110_can_ist,
> +				   flags, DEVICE_NAME, priv);
> +	if (ret) {
> +		dev_err(&spi->dev, "failed to acquire irq %d\n", spi->irq);

add propoer goto targets at the and of this function, for easier error
handling cleanup. This mean basically get rid of hi3110_open_clean(net).

> +		hi3110_power_enable(priv->transceiver, 0);
> +		close_candev(net);
> +		goto open_unlock;
> +	}
> +
> +	priv->wq = alloc_workqueue("hi3110_wq", WQ_FREEZABLE | WQ_MEM_RECLAIM,
> +			   0);
> +	INIT_WORK(&priv->tx_work, hi3110_tx_work_handler);
> +	INIT_WORK(&priv->restart_work, hi3110_restart_work_handler);
> +
> +	ret = hi3110_hw_reset(spi);
> +	if (ret) {
> +		hi3110_open_clean(net);
> +		goto open_unlock;
> +	}
> +	ret = hi3110_setup(net, priv, spi);
> +	if (ret) {
> +		hi3110_open_clean(net);
> +		goto open_unlock;
> +	}
> +	ret = hi3110_set_normal_mode(spi);
> +	if (ret) {
> +		hi3110_open_clean(net);
> +		goto open_unlock;
> +	}
> +	can_led_event(net, CAN_LED_EVENT_OPEN);
> +	netif_wake_queue(net);
> +
> +open_unlock:
> +	mutex_unlock(&priv->hi3110_lock);
> +	return ret;
> +}
> +
> +static const struct net_device_ops hi3110_netdev_ops = {
> +	.ndo_open = hi3110_open,
> +	.ndo_stop = hi3110_stop,
> +	.ndo_start_xmit = hi3110_hard_start_xmit,
> +};
> +
> +static const struct of_device_id hi3110_of_match[] = {
> +	{
> +		.compatible	= "holt,hi3110",
> +		.data		= (void *)CAN_HI3110_HI3110,
> +	},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(of, hi3110_of_match);
> +
> +static const struct spi_device_id hi3110_id_table[] = {
> +	{
> +		.name		= "hi3110",
> +		.driver_data	= (kernel_ulong_t)CAN_HI3110_HI3110,
> +	},
> +	{ }
> +};
> +MODULE_DEVICE_TABLE(spi, hi3110_id_table);
> +
> +static int hi3110_can_probe(struct spi_device *spi)
> +{
> +	const struct of_device_id *of_id = of_match_device(hi3110_of_match,
> +							   &spi->dev);
> +	struct net_device *net;
> +	struct hi3110_priv *priv;
> +	struct clk *clk;
> +	int freq, ret;
> +
> +	clk = devm_clk_get(&spi->dev, NULL);
> +	if (IS_ERR(clk)) {
> +		dev_err(&spi->dev, "no CAN clock source defined\n");
> +		return PTR_ERR(clk);
> +	}
> +	freq = clk_get_rate(clk);
> +
> +	/* Sanity check */
> +	if (freq > 40000000)
> +		return -ERANGE;
> +
> +	/* Allocate can/net device */
> +	net = alloc_candev(sizeof(struct hi3110_priv), TX_ECHO_SKB_MAX);
> +	if (!net)
> +		return -ENOMEM;
> +
> +	if (!IS_ERR(clk)) {
> +		ret = clk_prepare_enable(clk);
> +		if (ret)
> +			goto out_free;
> +	}
> +
> +	net->netdev_ops = &hi3110_netdev_ops;
> +	net->flags |= IFF_ECHO;
> +
> +	priv = netdev_priv(net);
> +	priv->can.bittiming_const = &hi3110_bittiming_const;
> +	priv->can.do_set_mode = hi3110_do_set_mode;
> +	priv->can.clock.freq = freq / 2;
> +	priv->can.ctrlmode_supported = CAN_CTRLMODE_3_SAMPLES |
> +		CAN_CTRLMODE_LOOPBACK | CAN_CTRLMODE_LISTENONLY;
> +	if (of_id)
> +		priv->model = (enum hi3110_model)of_id->data;
> +	else
> +		priv->model = spi_get_device_id(spi)->driver_data;
> +	priv->net = net;
> +	priv->clk = clk;
> +
> +	spi_set_drvdata(spi, priv);
> +
> +	/* Configure the SPI bus */
> +	spi->bits_per_word = 8;
> +	ret = spi_setup(spi);
> +	if (ret)
> +		goto out_clk;
> +
> +	priv->power = devm_regulator_get_optional(&spi->dev, "vdd");
> +	priv->transceiver = devm_regulator_get_optional(&spi->dev, "xceiver");
> +	if ((PTR_ERR(priv->power) == -EPROBE_DEFER) ||
> +	    (PTR_ERR(priv->transceiver) == -EPROBE_DEFER)) {
> +		ret = -EPROBE_DEFER;
> +		goto out_clk;
> +	}
> +
> +	ret = hi3110_power_enable(priv->power, 1);
> +	if (ret)
> +		goto out_clk;
> +
> +	priv->spi = spi;
> +	mutex_init(&priv->hi3110_lock);
> +
> +	/* If requested, allocate DMA buffers */
> +	if (hi3110_enable_dma) {
> +		spi->dev.coherent_dma_mask = ~0;
> +
> +		/* Minimum coherent DMA allocation is PAGE_SIZE, so allocate
> +		 * that much and share it between Tx and Rx DMA buffers.
> +		 */
> +		priv->spi_tx_buf = dmam_alloc_coherent(&spi->dev,
> +						      PAGE_SIZE,
> +						      &priv->spi_tx_dma,
> +						      GFP_DMA);
> +
> +		if (priv->spi_tx_buf) {
> +			priv->spi_rx_buf = (priv->spi_tx_buf + (PAGE_SIZE / 2));
> +			priv->spi_rx_dma = (dma_addr_t)(priv->spi_tx_dma +
> +							(PAGE_SIZE / 2));
> +		} else {
> +			/* Fall back to non-DMA */
> +			hi3110_enable_dma = 0;
> +		}
> +	}
> +
> +	/* Allocate non-DMA buffers */
> +	if (!hi3110_enable_dma) {
> +		priv->spi_tx_buf = devm_kzalloc(&spi->dev, RX_BUF_LEN,
> +				GFP_KERNEL);
> +		if (!priv->spi_tx_buf) {
> +			ret = -ENOMEM;
> +			goto error_probe;
> +		}
> +		priv->spi_rx_buf = devm_kzalloc(&spi->dev, RX_BUF_LEN,
> +				GFP_KERNEL);
> +
> +		if (!priv->spi_rx_buf) {
> +			ret = -ENOMEM;
> +			goto error_probe;
> +		}
> +	}
> +
> +	SET_NETDEV_DEV(net, &spi->dev);
> +
> +	ret = hi3110_hw_probe(spi);
> +	if (ret) {
> +		if (ret == -ENODEV)
> +			dev_err(&spi->dev, "Cannot initialize %x. Wrong wiring?\n",
> +				priv->model);
> +		goto error_probe;
> +	}
> +	hi3110_hw_sleep(spi);
> +
> +	ret = register_candev(net);
> +	if (ret)
> +		goto error_probe;
> +
> +	devm_can_led_init(net);
> +	netdev_info(net, "%x successfully initialized.\n", priv->model);
> +
> +	return 0;
> +
> +error_probe:
> +	hi3110_power_enable(priv->power, 0);
> +
> +out_clk:
> +	if (!IS_ERR(clk))
> +		clk_disable_unprepare(clk);
> +
> +out_free:
> +	free_candev(net);
> +
> +	dev_err(&spi->dev, "Probe failed, err=%d\n", -ret);
> +	return ret;
> +}
> +
> +static int hi3110_can_remove(struct spi_device *spi)
> +{
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +	struct net_device *net = priv->net;
> +
> +	unregister_candev(net);
> +
> +	hi3110_power_enable(priv->power, 0);
> +
> +	if (!IS_ERR(priv->clk))
> +		clk_disable_unprepare(priv->clk);
> +
> +	free_candev(net);
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused hi3110_can_suspend(struct device *dev)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +	struct net_device *net = priv->net;
> +
> +	priv->force_quit = 1;
> +	disable_irq(spi->irq);
> +
> +	/* Note: at this point neither IST nor workqueues are running.
> +	 * open/stop cannot be called anyway so locking is not needed
> +	 */
> +	if (netif_running(net)) {
> +		netif_device_detach(net);
> +
> +		hi3110_hw_sleep(spi);
> +		hi3110_power_enable(priv->transceiver, 0);
> +		priv->after_suspend = AFTER_SUSPEND_UP;
> +	} else {
> +		priv->after_suspend = AFTER_SUSPEND_DOWN;
> +	}
> +
> +	if (!IS_ERR_OR_NULL(priv->power)) {
> +		regulator_disable(priv->power);
> +		priv->after_suspend |= AFTER_SUSPEND_POWER;
> +	}
> +
> +	return 0;
> +}
> +
> +static int __maybe_unused hi3110_can_resume(struct device *dev)
> +{
> +	struct spi_device *spi = to_spi_device(dev);
> +	struct hi3110_priv *priv = spi_get_drvdata(spi);
> +
> +	if (priv->after_suspend & AFTER_SUSPEND_POWER)
> +		hi3110_power_enable(priv->power, 1);
> +
> +	if (priv->after_suspend & AFTER_SUSPEND_UP) {
> +		hi3110_power_enable(priv->transceiver, 1);
> +		queue_work(priv->wq, &priv->restart_work);
> +	} else {
> +		priv->after_suspend = 0;
> +	}
> +
> +	priv->force_quit = 0;
> +	enable_irq(spi->irq);
> +	return 0;
> +}
> +
> +static SIMPLE_DEV_PM_OPS(hi3110_can_pm_ops, hi3110_can_suspend,
> +	hi3110_can_resume);
> +
> +static struct spi_driver hi3110_can_driver = {
> +	.driver = {
> +		.name = DEVICE_NAME,
> +		.of_match_table = hi3110_of_match,
> +		.pm = &hi3110_can_pm_ops,
> +	},
> +	.id_table = hi3110_id_table,
> +	.probe = hi3110_can_probe,
> +	.remove = hi3110_can_remove,
> +};
> +
> +module_spi_driver(hi3110_can_driver);
> +
> +MODULE_AUTHOR("Akshay Bhat <akshay.bhat@xxxxxxxxxxx>");
> +MODULE_AUTHOR("Casey Fitzpatrick <casey.fitzpatrick@xxxxxxxxxxx>");
> +MODULE_DESCRIPTION("Holt HI-3110 CAN driver");
> +MODULE_LICENSE("GPL v2");
> 

Marc

-- 
Pengutronix e.K.                  | Marc Kleine-Budde           |
Industrial Linux Solutions        | Phone: +49-231-2826-924     |
Vertretung West/Dortmund          | Fax:   +49-5121-206917-5555 |
Amtsgericht Hildesheim, HRA 2686  | http://www.pengutronix.de   |

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