From mboxrd@z Thu Jan  1 00:00:00 1970
From: Wolfgang Grandegger <wg@grandegger.com>
Subject: Re: [PATCH v6 4/4] can: tcan4x5x: Add tcan4x5x driver to the kernel
Date: Mon, 4 Mar 2019 19:29:32 +0100
Message-ID: <1b66dbcc-8fa9-5ad4-6f30-a397d0779cb2@grandegger.com>
References: <20190301185043.9037-1-dmurphy@ti.com>
 <20190301185043.9037-4-dmurphy@ti.com>
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To: Dan Murphy <dmurphy@ti.com>, mkl@pengutronix.de, davem@davemloft.net
Cc: linux-can@vger.kernel.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org
List-Id: linux-can.vger.kernel.org

Hello Dan,

Am 01.03.19 um 19:50 schrieb Dan Murphy:
> Add the TCAN4x5x SPI CAN driver.  This device uses the
> Bosch MCAN IP core along with a SPI interface map.
> Register to the MCAN common core code to manage the MCAN IP.
> 
> This device has a special method to indicate a write/read
> operation on the data payload.
> 
> Signed-off-by: Dan Murphy <dmurphy@ti.com>
> ---
> 
> v6 - Updated Kconfig help and added REGMAP_SPI dependency, fixed coding style issues,
> removed setting GPIO high in wake routine, change -EIO to return ret in init and
> setup functions - https://lore.kernel.org/patchwork/patch/1042443/
> 
>  drivers/net/can/m_can/Kconfig    |   9 +
>  drivers/net/can/m_can/Makefile   |   1 +
>  drivers/net/can/m_can/tcan4x5x.c | 529 +++++++++++++++++++++++++++++++
>  3 files changed, 539 insertions(+)
>  create mode 100644 drivers/net/can/m_can/tcan4x5x.c
> 
> diff --git a/drivers/net/can/m_can/Kconfig b/drivers/net/can/m_can/Kconfig
> index f7119fd72df4..cf4f32765efa 100644
> --- a/drivers/net/can/m_can/Kconfig
> +++ b/drivers/net/can/m_can/Kconfig
> @@ -12,3 +12,12 @@ config CAN_M_CAN_PLATFORM
>  	  Say Y here if you want support for IO Mapped Bosch M_CAN controller.
>  	  This support is for devices that have the Bosch M_CAN controller
>  	  IP embedded into the device and the IP is IO Mapped to the processor.
> +
> +config CAN_M_CAN_TCAN4X5X
> +	depends on CAN_M_CAN
> +	depends on REGMAP_SPI
> +	tristate "TCAN4X5X M_CAN device"
> +	---help---
> +	  Say Y here if you want support for Texas Instruments TCAN4x5x
> +	  M_CAN controller.  This device is a peripherial device that uses the
> +	  SPI bus for communication.
> diff --git a/drivers/net/can/m_can/Makefile b/drivers/net/can/m_can/Makefile
> index 057bbcdb3c74..e77f0eccff97 100644
> --- a/drivers/net/can/m_can/Makefile
> +++ b/drivers/net/can/m_can/Makefile
> @@ -4,3 +4,4 @@
>  
>  obj-$(CONFIG_CAN_M_CAN) += m_can.o
>  obj-$(CONFIG_CAN_M_CAN_PLATFORM) += m_can_platform.o
> +obj-$(CONFIG_CAN_M_CAN_TCAN4X5X) += tcan4x5x.o
> diff --git a/drivers/net/can/m_can/tcan4x5x.c b/drivers/net/can/m_can/tcan4x5x.c
> new file mode 100644
> index 000000000000..a91b976bb522
> --- /dev/null
> +++ b/drivers/net/can/m_can/tcan4x5x.c
> @@ -0,0 +1,529 @@
> +// SPDX-License-Identifier: GPL-2.0
> +// SPI to CAN driver for the Texas Instruments TCAN4x5x
> +// Copyright (C) 2018-19 Texas Instruments Incorporated - http://www.ti.com/
> +
> +#include <linux/regmap.h>
> +#include <linux/spi/spi.h>
> +
> +#include <linux/regulator/consumer.h>
> +#include <linux/gpio/consumer.h>
> +
> +#include "m_can.h"
> +
> +#define DEVICE_NAME "tcan4x5x"
> +#define TCAN4X5X_EXT_CLK_DEF	40000000
> +
> +#define TCAN4X5X_DEV_ID0	0x00
> +#define TCAN4X5X_DEV_ID1	0x04
> +#define TCAN4X5X_REV		0x08
> +#define TCAN4X5X_STATUS		0x0C
> +#define TCAN4X5X_ERROR_STATUS	0x10
> +#define TCAN4X5X_CONTROL	0x14
> +
> +#define TCAN4X5X_CONFIG		0x800
> +#define TCAN4X5X_TS_PRESCALE	0x804
> +#define TCAN4X5X_TEST_REG	0x808
> +#define TCAN4X5X_INT_FLAGS	0x820
> +#define TCAN4X5X_MCAN_INT_REG	0x824
> +#define TCAN4X5X_INT_EN		0x830
> +
> +/* Interrupt bits */
> +#define TCAN4X5X_CANBUSTERMOPEN_INT_EN	BIT(30)
> +#define TCAN4X5X_CANHCANL_INT_EN	BIT(29)
> +#define TCAN4X5X_CANHBAT_INT_EN		BIT(28)
> +#define TCAN4X5X_CANLGND_INT_EN		BIT(27)
> +#define TCAN4X5X_CANBUSOPEN_INT_EN	BIT(26)
> +#define TCAN4X5X_CANBUSGND_INT_EN	BIT(25)
> +#define TCAN4X5X_CANBUSBAT_INT_EN	BIT(24)
> +#define TCAN4X5X_UVSUP_INT_EN		BIT(22)
> +#define TCAN4X5X_UVIO_INT_EN		BIT(21)
> +#define TCAN4X5X_TSD_INT_EN		BIT(19)
> +#define TCAN4X5X_ECCERR_INT_EN		BIT(16)
> +#define TCAN4X5X_CANINT_INT_EN		BIT(15)
> +#define TCAN4X5X_LWU_INT_EN		BIT(14)
> +#define TCAN4X5X_CANSLNT_INT_EN		BIT(10)
> +#define TCAN4X5X_CANDOM_INT_EN		BIT(8)
> +#define TCAN4X5X_CANBUS_ERR_INT_EN	BIT(5)
> +#define TCAN4X5X_BUS_FAULT		BIT(4)
> +#define TCAN4X5X_MCAN_INT		BIT(1)
> +#define TCAN4X5X_ENABLE_TCAN_INT	(TCAN4X5X_MCAN_INT | \
> +					TCAN4X5X_BUS_FAULT | \
> +					TCAN4X5X_CANBUS_ERR_INT_EN | \
> +					TCAN4X5X_CANINT_INT_EN)
> +
> +/* MCAN Interrupt bits */
> +#define TCAN4X5X_MCAN_IR_ARA		BIT(29)
> +#define TCAN4X5X_MCAN_IR_PED		BIT(28)
> +#define TCAN4X5X_MCAN_IR_PEA		BIT(27)
> +#define TCAN4X5X_MCAN_IR_WD		BIT(26)
> +#define TCAN4X5X_MCAN_IR_BO		BIT(25)
> +#define TCAN4X5X_MCAN_IR_EW		BIT(24)
> +#define TCAN4X5X_MCAN_IR_EP		BIT(23)
> +#define TCAN4X5X_MCAN_IR_ELO		BIT(22)
> +#define TCAN4X5X_MCAN_IR_BEU		BIT(21)
> +#define TCAN4X5X_MCAN_IR_BEC		BIT(20)
> +#define TCAN4X5X_MCAN_IR_DRX		BIT(19)
> +#define TCAN4X5X_MCAN_IR_TOO		BIT(18)
> +#define TCAN4X5X_MCAN_IR_MRAF		BIT(17)
> +#define TCAN4X5X_MCAN_IR_TSW		BIT(16)
> +#define TCAN4X5X_MCAN_IR_TEFL		BIT(15)
> +#define TCAN4X5X_MCAN_IR_TEFF		BIT(14)
> +#define TCAN4X5X_MCAN_IR_TEFW		BIT(13)
> +#define TCAN4X5X_MCAN_IR_TEFN		BIT(12)
> +#define TCAN4X5X_MCAN_IR_TFE		BIT(11)
> +#define TCAN4X5X_MCAN_IR_TCF		BIT(10)
> +#define TCAN4X5X_MCAN_IR_TC		BIT(9)
> +#define TCAN4X5X_MCAN_IR_HPM		BIT(8)
> +#define TCAN4X5X_MCAN_IR_RF1L		BIT(7)
> +#define TCAN4X5X_MCAN_IR_RF1F		BIT(6)
> +#define TCAN4X5X_MCAN_IR_RF1W		BIT(5)
> +#define TCAN4X5X_MCAN_IR_RF1N		BIT(4)
> +#define TCAN4X5X_MCAN_IR_RF0L		BIT(3)
> +#define TCAN4X5X_MCAN_IR_RF0F		BIT(2)
> +#define TCAN4X5X_MCAN_IR_RF0W		BIT(1)
> +#define TCAN4X5X_MCAN_IR_RF0N		BIT(0)
> +#define TCAN4X5X_ENABLE_MCAN_INT	(TCAN4X5X_MCAN_IR_TC | \
> +					TCAN4X5X_MCAN_IR_RF0N | \
> +					TCAN4X5X_MCAN_IR_RF1N | \
> +					TCAN4X5X_MCAN_IR_RF0F | \
> +					TCAN4X5X_MCAN_IR_RF1F)
> +#define TCAN4X5X_MRAM_START	0x8000
> +#define TCAN4X5X_MCAN_OFFSET	0x1000
> +#define TCAN4X5X_MAX_REGISTER	0x8fff
> +
> +#define TCAN4X5X_CLEAR_ALL_INT	0xffffffff
> +#define TCAN4X5X_SET_ALL_INT	0xffffffff
> +
> +#define TCAN4X5X_WRITE_CMD	(0x61 << 24)
> +#define TCAN4X5X_READ_CMD	(0x41 << 24)
> +
> +#define TCAN4X5X_MODE_SEL_MASK		(BIT(7) | BIT(6))
> +#define TCAN4X5X_MODE_SLEEP		0x00
> +#define TCAN4X5X_MODE_STANDBY		BIT(6)
> +#define TCAN4X5X_MODE_NORMAL		BIT(7)
> +
> +#define TCAN4X5X_SW_RESET	BIT(2)
> +
> +#define TCAN4X5X_MCAN_CONFIGURED	BIT(5)
> +#define TCAN4X5X_WATCHDOG_EN		BIT(3)
> +#define TCAN4X5X_WD_60_MS_TIMER		0
> +#define TCAN4X5X_WD_600_MS_TIMER	BIT(28)
> +#define TCAN4X5X_WD_3_S_TIMER		BIT(29)
> +#define TCAN4X5X_WD_6_S_TIMER		(BIT(28) | BIT(29))
> +
> +struct tcan4x5x_priv {
> +	struct regmap *regmap;
> +	struct spi_device *spi;
> +	struct mutex tcan4x5x_lock; /* SPI device lock */
> +
> +	struct m_can_classdev *mcan_dev;
> +
> +	struct gpio_desc *reset_gpio;
> +	struct gpio_desc *interrupt_gpio;
> +	struct gpio_desc *device_wake_gpio;
> +	struct gpio_desc *device_state_gpio;
> +	struct regulator *power;
> +
> +	/* Register based ip */
> +	int mram_start;
> +	int reg_offset;
> +};
> +
> +static struct can_bittiming_const tcan4x5x_bittiming_const = {
> +	.name = DEVICE_NAME,
> +	.tseg1_min = 2,
> +	.tseg1_max = 31,
> +	.tseg2_min = 2,
> +	.tseg2_max = 16,
> +	.sjw_max = 16,
> +	.brp_min = 1,
> +	.brp_max = 32,
> +	.brp_inc = 1,
> +};
> +
> +static struct can_bittiming_const tcan4x5x_data_bittiming_const = {
> +	.name = DEVICE_NAME,
> +	.tseg1_min = 1,
> +	.tseg1_max = 32,
> +	.tseg2_min = 1,
> +	.tseg2_max = 16,
> +	.sjw_max = 16,
> +	.brp_min = 1,
> +	.brp_max = 32,
> +	.brp_inc = 1,
> +};
> +
> +static void tcan4x5x_check_wake(struct tcan4x5x_priv *priv)
> +{
> +	int wake_state = 0;
> +
> +	if (priv->device_state_gpio)
> +		wake_state = gpiod_get_value(priv->device_state_gpio);
> +
> +	if (priv->device_wake_gpio && wake_state) {
> +		gpiod_set_value(priv->device_wake_gpio, 0);
> +		usleep_range(5, 50);
> +		gpiod_set_value(priv->device_wake_gpio, 1);
> +	}
> +}
> +
> +static int regmap_spi_gather_write(void *context, const void *reg,
> +				   size_t reg_len, const void *val,
> +				   size_t val_len)
> +{
> +	struct device *dev = context;
> +	struct spi_device *spi = to_spi_device(dev);
> +	struct spi_message m;
> +	u32 addr;
> +	struct spi_transfer t[2] = {
> +		{ .tx_buf = &addr, .len = reg_len, .cs_change = 0,},
> +		{ .tx_buf = val, .len = val_len, },
> +	};
> +
> +	addr = TCAN4X5X_WRITE_CMD | (*((u16 *)reg) << 8) | val_len >> 3;
> +
> +	spi_message_init(&m);
> +	spi_message_add_tail(&t[0], &m);
> +	spi_message_add_tail(&t[1], &m);
> +
> +	return spi_sync(spi, &m);
> +}
> +
> +static int tcan4x5x_regmap_write(void *context, const void *data, size_t count)
> +{
> +	u16 *reg = (u16 *)(data);
> +	const u32 *val = data + 4;
> +
> +	return regmap_spi_gather_write(context, reg, 4, val, count);
> +}
> +
> +static int regmap_spi_async_write(void *context,
> +				  const void *reg, size_t reg_len,
> +				  const void *val, size_t val_len,
> +				  struct regmap_async *a)
> +{
> +	return -ENOTSUPP;
> +}
> +
> +static struct regmap_async *regmap_spi_async_alloc(void)
> +{
> +	return NULL;
> +}
> +
> +static int tcan4x5x_regmap_read(void *context,
> +				const void *reg, size_t reg_size,
> +				void *val, size_t val_size)
> +{
> +	struct device *dev = context;
> +	struct spi_device *spi = to_spi_device(dev);
> +
> +	u32 addr = TCAN4X5X_READ_CMD | (*((u16 *)reg) << 8) | val_size >> 2;
> +
> +	return spi_write_then_read(spi, &addr, reg_size, (u32 *)val, val_size);
> +}
> +
> +static struct regmap_bus tcan4x5x_bus = {
> +	.write = tcan4x5x_regmap_write,
> +	.gather_write = regmap_spi_gather_write,
> +	.async_write = regmap_spi_async_write,
> +	.async_alloc = regmap_spi_async_alloc,
> +	.read = tcan4x5x_regmap_read,
> +	.read_flag_mask = 0x00,
> +	.reg_format_endian_default = REGMAP_ENDIAN_NATIVE,
> +	.val_format_endian_default = REGMAP_ENDIAN_NATIVE,
> +};
> +
> +static u32 tcan4x5x_read_reg(struct m_can_classdev *m_can_class, int reg)
> +{
> +	struct tcan4x5x_priv *priv = (struct tcan4x5x_priv *)m_can_class->device_data;
> +	u32 val;
> +
> +	tcan4x5x_check_wake(priv);
> +
> +	regmap_read(priv->regmap, priv->reg_offset + reg, &val);
> +
> +	return val;
> +}
> +
> +static u32 tcan4x5x_read_fifo(struct m_can_classdev *m_can_class,
> +			      int addr_offset)
> +{
> +	struct tcan4x5x_priv *priv = (struct tcan4x5x_priv *)m_can_class->device_data;
> +	u32 val;
> +
> +	tcan4x5x_check_wake(priv);
> +
> +	regmap_read(priv->regmap, priv->mram_start + addr_offset, &val);
> +
> +	return val;
> +}
> +
> +static int tcan4x5x_write_reg(struct m_can_classdev *m_can_class,
> +			      int reg, int val)
> +{
> +	struct tcan4x5x_priv *priv = (struct tcan4x5x_priv *)m_can_class->device_data;
> +
> +	tcan4x5x_check_wake(priv);
> +
> +	return regmap_write(priv->regmap, priv->reg_offset + reg, val);
> +}
> +
> +static int tcan4x5x_write_fifo(struct m_can_classdev *m_can_class,
> +			       int addr_offset, int val)
> +{
> +	struct tcan4x5x_priv *priv = (struct tcan4x5x_priv *)m_can_class->device_data;
> +
> +	tcan4x5x_check_wake(priv);
> +
> +	return regmap_write(priv->regmap, priv->mram_start + addr_offset, val);
> +}
> +
> +static int tcan4x5x_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 int tcan4x5x_write_tcan_reg(struct m_can_classdev *m_can_class,
> +				   int reg, int val)
> +{
> +	struct tcan4x5x_priv *priv = (struct tcan4x5x_priv *)m_can_class->device_data;
> +
> +	tcan4x5x_check_wake(priv);
> +
> +	return regmap_write(priv->regmap, reg, val);
> +}
> +
> +static int tcan4x5x_clear_interrupts(struct m_can_classdev *class_dev)
> +{
> +	struct tcan4x5x_priv *tcan4x5x = (struct tcan4x5x_priv *)class_dev->device_data;
> +	int ret;
> +
> +	tcan4x5x_check_wake(tcan4x5x);
> +
> +	ret = tcan4x5x_write_tcan_reg(class_dev, TCAN4X5X_STATUS,
> +				      TCAN4X5X_CLEAR_ALL_INT);
> +	if (ret)
> +		return ret;
> +
> +	ret = tcan4x5x_write_tcan_reg(class_dev, TCAN4X5X_MCAN_INT_REG,
> +				      TCAN4X5X_ENABLE_MCAN_INT);
> +	if (ret)
> +		return ret;
> +
> +	ret = tcan4x5x_write_tcan_reg(class_dev, TCAN4X5X_INT_FLAGS,
> +				      TCAN4X5X_CLEAR_ALL_INT);
> +	if (ret)
> +		return ret;
> +
> +	ret = tcan4x5x_write_tcan_reg(class_dev, TCAN4X5X_ERROR_STATUS,
> +				      TCAN4X5X_CLEAR_ALL_INT);
> +	if (ret)
> +		return ret;
> +
> +	return ret;
> +}

Hm, handling the interrupt seems to be a quite heavy operation. How does
the device and system digest small messages (dlc=0) coming in at a very
high rate?

Any chance to optimize accesses be reading more than on word?

Wolfgang.