Subject: Re: [PATCH net-next-2.6 v4 1/1] can: c_can: Added support for Bosch C_CAN controller

From: Wolfgang Grandegger <[email-masked]>
Date: Tue, 11 Jan 2011 14:16:53 +0100

Hi Bhupesh,

some final nitpicking as you need to fix Marc remarks anyway...

On 01/11/2011 12:49 PM, Bhupesh Sharma wrote:
> Bosch C_CAN controller is a full-CAN implementation which is compliant
> to CAN protocol version 2.0 part A and B. Bosch C_CAN user manual can be
> obtained from:
> http://www.semiconductors.bosch.de/media/en/pdf/ipmodules_1/
> c_can/users_manual_c_can.pdf
> 
> This patch adds the support for this controller.
> The following are the design choices made while writing the controller
> driver:
> 1. Interface Register set IF1 has be used only in the current design.
> 2. Out of the 32 Message objects available, 16 are kept aside for RX
>    purposes and the rest for TX purposes.
> 3. NAPI implementation is such that both the TX and RX paths function
>    in polling mode.
> 
> Changes since V3:
> 1. Corrected commenting style.
> 2. Removing *non-required* header files from driver files.
> 3. Removed extra *non-required* outer brackets globally.
> 4. Implemented and used a inline routine to check BUSY status.
> 5. Added a board-specific param *priv* inside the c_can_priv struct.
> 
> Signed-off-by: Bhupesh Sharma <[email-masked]>

...
> +++ b/drivers/net/can/c_can/c_can.h
> @@ -0,0 +1,235 @@
> +/*
> + * CAN bus driver for Bosch C_CAN controller
> + *
> + * Copyright (C) 2010 ST Microelectronics
> + * Bhupesh Sharma <[email-masked]>
> + *
> + * Borrowed heavily from the C_CAN driver originally written by:
> + * Copyright (C) 2007
> + * - Sascha Hauer, Marc Kleine-Budde, Pengutronix <[email-masked]>
> + * - Simon Kallweit, intefo AG <simon.kallweit-+G9qxTFKJT/[email-masked]>
> + *
> + * TX and RX NAPI implementation has been borrowed from at91 CAN driver
> + * written by:
> + * Copyright
> + * (C) 2007 by Hans J. Koch <[email-masked]>
> + * (C) 2008, 2009 by Marc Kleine-Budde <[email-masked]>
> + *
> + * Bosch C_CAN controller is compliant to CAN protocol version 2.0 part A and B.
> + * Bosch C_CAN user manual can be obtained from:
> + * http://www.semiconductors.bosch.de/media/en/pdf/ipmodules_1/c_can/
> + * users_manual_c_can.pdf
> + *
> + * This file is licensed under the terms of the GNU General Public
> + * License version 2. This program is licensed "as is" without any
> + * warranty of any kind, whether express or implied.
> + */
> +
> +#ifndef C_CAN_H
> +#define C_CAN_H
> +
> +/* control register */
> +#define CONTROL_TEST		BIT(7)
> +#define CONTROL_CCE		BIT(6)
> +#define CONTROL_DISABLE_AR	BIT(5)
> +#define CONTROL_ENABLE_AR	(0 << 5)
> +#define CONTROL_EIE		BIT(3)
> +#define CONTROL_SIE		BIT(2)
> +#define CONTROL_IE		BIT(1)
> +#define CONTROL_INIT		BIT(0)
> +
> +/* test register */
> +#define TEST_RX			BIT(7)
> +#define TEST_TX1		BIT(6)
> +#define TEST_TX2		BIT(5)
> +#define TEST_LBACK		BIT(4)
> +#define TEST_SILENT		BIT(3)
> +#define TEST_BASIC		BIT(2)
> +
> +/* status register */
> +#define STATUS_BOFF		BIT(7)
> +#define STATUS_EWARN		BIT(6)
> +#define STATUS_EPASS		BIT(5)
> +#define STATUS_RXOK		BIT(4)
> +#define STATUS_TXOK		BIT(3)
> +#define STATUS_LEC_MASK		0x07
> +
> +/* error counter register */
> +#define ERR_COUNTER_TEC_MASK	0xff
> +#define ERR_COUNTER_TEC_SHIFT	0
> +#define ERR_COUNTER_REC_SHIFT	8
> +#define ERR_COUNTER_REC_MASK	(0x7f << ERR_COUNTER_REC_SHIFT)
> +#define ERR_COUNTER_RP_SHIFT	15
> +#define ERR_COUNTER_RP_MASK	(0x1 << ERR_COUNTER_RP_SHIFT)

s/ERR_COUNTER/ERR_CNT/ to match the member name.

> +
> +/* bit-timing register */
> +#define BTR_BRP_MASK		0x3f
> +#define BTR_BRP_SHIFT		0
> +#define BTR_SJW_SHIFT		6
> +#define BTR_SJW_MASK		(0x3 << BTR_SJW_SHIFT)
> +#define BTR_TSEG1_SHIFT		8
> +#define BTR_TSEG1_MASK		(0xf << BTR_TSEG1_SHIFT)
> +#define BTR_TSEG2_SHIFT		12
> +#define BTR_TSEG2_MASK		(0x7 << BTR_TSEG2_SHIFT)
> +
> +/* brp extension register */
> +#define BRP_EXT_BRPE_MASK	0x0f
> +#define BRP_EXT_BRPE_SHIFT	0
> +
> +/* IFx command request */
> +#define IF_COMR_BUSY		BIT(15)
> +
> +/* IFx command mask */
> +#define IF_COMM_WR		BIT(7)
> +#define IF_COMM_MASK		BIT(6)
> +#define IF_COMM_ARB		BIT(5)
> +#define IF_COMM_CONTROL		BIT(4)
> +#define IF_COMM_CLR_INT_PND	BIT(3)
> +#define IF_COMM_TXRQST		BIT(2)
> +#define IF_COMM_DATAA		BIT(1)
> +#define IF_COMM_DATAB		BIT(0)
> +#define IF_COMM_ALL		(IF_COMM_MASK | IF_COMM_ARB | \
> +				IF_COMM_CONTROL | IF_COMM_TXRQST | \
> +				IF_COMM_DATAA | IF_COMM_DATAB)
> +
> +/* IFx arbitration */
> +#define IF_ARB_MSGVAL		BIT(15)
> +#define IF_ARB_MSGXTD		BIT(14)
> +#define IF_ARB_TRANSMIT		BIT(13)
> +
> +/* IFx message control */
> +#define IF_MCONT_NEWDAT		BIT(15)
> +#define IF_MCONT_MSGLST		BIT(14)
> +#define IF_MCONT_CLR_MSGLST	(0 << 14)
> +#define IF_MCONT_INTPND		BIT(13)
> +#define IF_MCONT_UMASK		BIT(12)
> +#define IF_MCONT_TXIE		BIT(11)
> +#define IF_MCONT_RXIE		BIT(10)
> +#define IF_MCONT_RMTEN		BIT(9)
> +#define IF_MCONT_TXRQST		BIT(8)
> +#define IF_MCONT_EOB		BIT(7)
> +#define IF_MCONT_DLC_MASK	0xf
> +
> +/*
> + * IFx register masks:
> + * allow easy operation on 16-bit registers when the
> + * argument is 32-bit instead
> + */
> +#define IFX_WRITE_LOW_16BIT(x)	((x) & 0xFFFF)
> +#define IFX_WRITE_HIGH_16BIT(x)	(((x) & 0xFFFF0000) >> 16)
> +
> +/* message object split */
> +#define C_CAN_NO_OF_OBJECTS	31
> +#define C_CAN_MSG_OBJ_RX_NUM	16
> +#define C_CAN_MSG_OBJ_TX_NUM	16
> +
> +#define C_CAN_MSG_OBJ_RX_FIRST	0
> +#define C_CAN_MSG_OBJ_RX_LAST	(C_CAN_MSG_OBJ_RX_FIRST + \
> +				C_CAN_MSG_OBJ_RX_NUM - 1)
> +
> +#define C_CAN_MSG_OBJ_TX_FIRST	(C_CAN_MSG_OBJ_RX_LAST + 1)
> +#define C_CAN_MSG_OBJ_TX_LAST	(C_CAN_MSG_OBJ_TX_FIRST + \
> +				C_CAN_MSG_OBJ_TX_NUM - 1)
> +
> +#define C_CAN_MSG_OBJ_RX_SPLIT	8
> +#define C_CAN_MSG_RX_LOW_LAST	(C_CAN_MSG_OBJ_RX_SPLIT - 1)
> +
> +#define C_CAN_NEXT_MSG_OBJ_MASK	(C_CAN_MSG_OBJ_TX_NUM - 1)
> +#define RECEIVE_OBJECT_BITS	0x0000ffff
> +
> +/* status interrupt */
> +#define STATUS_INTERRUPT	0x8000
> +
> +/* global interrupt masks */
> +#define ENABLE_ALL_INTERRUPTS	1
> +#define DISABLE_ALL_INTERRUPTS	0
> +
> +/* minimum timeout for checking BUSY status */
> +#define MIN_TIMEOUT_VALUE	6
> +
> +/* napi related */
> +#define C_CAN_NAPI_WEIGHT	C_CAN_MSG_OBJ_RX_NUM
> +
> +/* c_can IF registers */
> +struct c_can_if_regs {
> +	u16 com_reg;
> +	u16 com_mask;
> +	u16 mask1;
> +	u16 mask2;
> +	u16 arb1;
> +	u16 arb2;
> +	u16 msg_cntrl;
> +	u16 data[4];
> +	u16 _reserved[13];
> +};
> +
> +/* c_can hardware registers */
> +struct c_can_regs {
> +	u16 control;
> +	u16 status;
> +	u16 err_cnt;
> +	u16 btr;
> +	u16 interrupt;
> +	u16 test;
> +	u16 brp_ext;
> +	u16 _reserved1;
> +	struct c_can_if_regs intf[2]; /* [0] = IF1 and [1] = IF2 */

I not happy with the name "intf". Sounds more like an interrupt related
property. Above you already use the prefix IF_ for the corresponding
macro definitions and somewhere else the name "iface".

Wolfgang.