Date:	Wed, 12 Jan 2011 16:38:04 +0800
From:	Bhupesh SHARMA <bhupesh.sharma@...com>
To:	Wolfgang Grandegger <wg@...ndegger.com>
Cc:	"Socketcan-core@...ts.berlios.de" <Socketcan-core@...ts.berlios.de>,
	"netdev@...r.kernel.org" <netdev@...r.kernel.org>,
	Marc Kleine-Budde <mkl@...gutronix.de>,
	David Miller <davem@...emloft.net>
Subject: RE: [PATCH net-next-2.6 v4 1/1] can: c_can: Added support for Bosch
 C_CAN controller

Hi Wolfgang,

> On 01/12/2011 04:30 AM, Bhupesh SHARMA wrote:
> > Hi Wolfgang,
> >
> >> -----Original Message-----
> >> From: Wolfgang Grandegger [mailto:wg@...ndegger.com]
> >> 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 <bhupesh.sharma@...com>
> >>
> >> ...
> >>> +++ 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 <bhupesh.sharma@...com>
> >>> + *
> >>> + * Borrowed heavily from the C_CAN driver originally written by:
> >>> + * Copyright (C) 2007
> >>> + * - Sascha Hauer, Marc Kleine-Budde, Pengutronix
> >> <s.hauer@...gutronix.de>
> >>> + * - Simon Kallweit, intefo AG <simon.kallweit@...efo.ch>
> >>> + *
> >>> + * TX and RX NAPI implementation has been borrowed from at91 CAN
> >> driver
> >>> + * written by:
> >>> + * Copyright
> >>> + * (C) 2007 by Hans J. Koch <hjk@...utronix.de>
> >>> + * (C) 2008, 2009 by Marc Kleine-Budde <kernel@...gutronix.de>
> >>> + *
> >>> + * 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.
> >
> > Ok.
> >
> >>> +
> >>> +/* 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".
> >
> > I tried using the name *if* suggested by you here but the compiler
> will complain
> > considering it as a usage of if-construct. Do you have a better name
> that we
> > can use here?
> 
> Oh, I was not aware ot that. Sorry for the noise! Then your old
> "ifregs"
> or "iface" would be fine, I think. I just see that the pch_can uses
> "ifregs" as well.
> 

Yes, I get checked the pch_can driver as well. It also uses the name *ifregs*.
Let's keep the name *ifregs* then.

Regards,
Bhupesh
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