Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755479Ab0LGLDP (ORCPT ); Tue, 7 Dec 2010 06:03:15 -0500 Received: from sm-d311v.smileserver.ne.jp ([203.211.202.206]:18138 "EHLO sm-d311v.smileserver.ne.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755321Ab0LGLDN (ORCPT ); Tue, 7 Dec 2010 06:03:13 -0500 Message-ID: <4CFE1517.8020906@dsn.okisemi.com> Date: Tue, 07 Dec 2010 20:05:59 +0900 From: Tomoya MORINAGA User-Agent: Mozilla/5.0 (X11; U; Linux i686; ja; rv:1.9.2.12) Gecko/20101027 Thunderbird/3.1.6 MIME-Version: 1.0 To: Wolfgang Grandegger , socketcan-core@lists.berlios.de, netdev@vger.kernel.org, linux-kernel@vger.kernel.org CC: qi.wang@intel.com, yong.y.wang@intel.com, andrew.chih.howe.khor@intel.com, joel.clark@intel.com, kok.howg.ewe@intel.com, margie.foster@intel.com Subject: [PATCH net-next-2.6 v8 06/20] CAN : Rename function/macro name Content-Type: text/plain; charset=ISO-2022-JP Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 17334 Lines: 470 For easy to read/understand, Rename function/macro name. Signed-off-by: Tomoya MORINAGA --- drivers/net/can/pch_can.c | 176 ++++++++++++++++++++------------------------- 1 files changed, 77 insertions(+), 99 deletions(-) diff --git a/drivers/net/can/pch_can.c b/drivers/net/can/pch_can.c index 5fc99cb..dd9ce16 100644 --- a/drivers/net/can/pch_can.c +++ b/drivers/net/can/pch_can.c @@ -32,8 +32,6 @@ #include #include -#define PCH_ENABLE 1 /* The enable flag */ -#define PCH_DISABLE 0 /* The disable flag */ #define PCH_CTRL_INIT BIT(0) /* The INIT bit of CANCONT register. */ #define PCH_CTRL_IE BIT(1) /* The IE bit of CAN control register */ #define PCH_CTRL_IE_SIE_EIE (BIT(3) | BIT(2) | BIT(1)) @@ -78,11 +76,12 @@ #define PCH_BUS_OFF BIT(7) /* bit position of certain controller bits. */ -#define PCH_BIT_BRP 0 -#define PCH_BIT_SJW 6 -#define PCH_BIT_TSEG1 8 -#define PCH_BIT_TSEG2 12 -#define PCH_BIT_BRPE_BRPE 6 +#define PCH_BIT_BRP_SHIFT 0 +#define PCH_BIT_SJW_SHIFT 6 +#define PCH_BIT_TSEG1_SHIFT 8 +#define PCH_BIT_TSEG2_SHIFT 12 +#define PCH_BIT_BRPE_BRPE_SHIFT 6 + #define PCH_MSK_BITT_BRP 0x3f #define PCH_MSK_BRPE_BRPE 0x3c0 #define PCH_MSK_CTRL_IE_SIE_EIE 0x07 @@ -170,19 +169,16 @@ struct pch_can_regs { struct pch_can_priv { struct can_priv can; - unsigned int can_num; struct pci_dev *dev; - int tx_enable[PCH_TX_OBJ_END]; - int rx_enable[PCH_TX_OBJ_END]; - int rx_link[PCH_TX_OBJ_END]; - unsigned int int_enables; - unsigned int int_stat; + u32 tx_enable[PCH_TX_OBJ_END]; + u32 rx_enable[PCH_TX_OBJ_END]; + u32 rx_link[PCH_TX_OBJ_END]; + u32 int_enables; struct net_device *ndev; - unsigned int msg_obj[PCH_TX_OBJ_END]; struct pch_can_regs __iomem *regs; struct napi_struct napi; - unsigned int tx_obj; /* Point next Tx Obj index */ - unsigned int use_msi; + int tx_obj; /* Point next Tx Obj index */ + int use_msi; }; static struct can_bittiming_const pch_can_bittiming_const = { @@ -245,14 +241,27 @@ static void pch_can_set_optmode(struct pch_can_priv *priv) iowrite32(reg_val, &priv->regs->opt); } +static void pch_can_rw_msg_obj(void __iomem *creq_addr, u32 num) +{ + int counter = PCH_COUNTER_LIMIT; + u32 ifx_creq; + + iowrite32(num, creq_addr); + while (counter) { + ifx_creq = ioread32(creq_addr) & PCH_IF_CREQ_BUSY; + if (!ifx_creq) + break; + counter--; + udelay(1); + } + if (!counter) + pr_err("%s:IF1 BUSY Flag is set forever.\n", __func__); +} + static void pch_can_set_int_enables(struct pch_can_priv *priv, enum pch_can_mode interrupt_no) { switch (interrupt_no) { - case PCH_CAN_ENABLE: - pch_can_bit_set(&priv->regs->cont, PCH_CTRL_IE); - break; - case PCH_CAN_DISABLE: pch_can_bit_clear(&priv->regs->cont, PCH_CTRL_IE); break; @@ -271,25 +280,8 @@ static void pch_can_set_int_enables(struct pch_can_priv *priv, } } -static void pch_can_check_if_busy(u32 __iomem *creq_addr, u32 num) -{ - u32 counter = PCH_COUNTER_LIMIT; - u32 ifx_creq; - - iowrite32(num, creq_addr); - while (counter) { - ifx_creq = ioread32(creq_addr) & PCH_IF_CREQ_BUSY; - if (!ifx_creq) - break; - counter--; - udelay(1); - } - if (!counter) - pr_err("%s:IF1 BUSY Flag is set forever.\n", __func__); -} - static void pch_can_set_rxtx(struct pch_can_priv *priv, u32 buff_num, - u32 set, enum pch_ifreg dir) + int set, enum pch_ifreg dir) { u32 ie; @@ -300,27 +292,27 @@ static void pch_can_set_rxtx(struct pch_can_priv *priv, u32 buff_num, /* Reading the receive buffer data from RAM to Interface1 registers */ iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[dir].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[dir].creq, buff_num); + pch_can_rw_msg_obj(&priv->regs->ifregs[dir].creq, buff_num); /* Setting the IF1MASK1 register to access MsgVal and RxIE bits */ iowrite32(PCH_CMASK_RDWR | PCH_CMASK_ARB | PCH_CMASK_CTRL, &priv->regs->ifregs[dir].cmask); - if (set == PCH_ENABLE) { + if (set) { /* Setting the MsgVal and RxIE bits */ pch_can_bit_set(&priv->regs->ifregs[dir].mcont, ie); pch_can_bit_set(&priv->regs->ifregs[dir].id2, PCH_ID_MSGVAL); - } else if (set == PCH_DISABLE) { + } else { /* Resetting the MsgVal and RxIE bits */ pch_can_bit_clear(&priv->regs->ifregs[dir].mcont, ie); pch_can_bit_clear(&priv->regs->ifregs[dir].id2, PCH_ID_MSGVAL); } - pch_can_check_if_busy(&priv->regs->ifregs[dir].creq, buff_num); + pch_can_rw_msg_obj(&priv->regs->ifregs[dir].creq, buff_num); } -static void pch_can_set_rx_all(struct pch_can_priv *priv, u32 set) +static void pch_can_set_rx_all(struct pch_can_priv *priv, int set) { int i; @@ -329,7 +321,7 @@ static void pch_can_set_rx_all(struct pch_can_priv *priv, u32 set) pch_can_set_rxtx(priv, i, set, PCH_RX_IFREG); } -static void pch_can_set_tx_all(struct pch_can_priv *priv, u32 set) +static void pch_can_set_tx_all(struct pch_can_priv *priv, int set) { int i; @@ -338,16 +330,16 @@ static void pch_can_set_tx_all(struct pch_can_priv *priv, u32 set) pch_can_set_rxtx(priv, i, set, PCH_TX_IFREG); } -static int pch_can_int_pending(struct pch_can_priv *priv) +static u32 pch_can_int_pending(struct pch_can_priv *priv) { return ioread32(&priv->regs->intr) & 0xffff; } -static void pch_can_clear_buffers(struct pch_can_priv *priv) +static void pch_can_clear_if_buffers(struct pch_can_priv *priv) { - int i; + int i; /* Msg Obj ID (1~32) */ - for (i = PCH_RX_OBJ_START; i <= PCH_RX_OBJ_END; i++) { + for (i = PCH_RX_OBJ_START; i <= PCH_TX_OBJ_END; i++) { iowrite32(PCH_CMASK_RX_TX_SET, &priv->regs->ifregs[0].cmask); iowrite32(0xffff, &priv->regs->ifregs[0].mask1); iowrite32(0xffff, &priv->regs->ifregs[0].mask2); @@ -361,24 +353,7 @@ static void pch_can_clear_buffers(struct pch_can_priv *priv) iowrite32(PCH_CMASK_RDWR | PCH_CMASK_MASK | PCH_CMASK_ARB | PCH_CMASK_CTRL, &priv->regs->ifregs[0].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, i); - } - - for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++) { - iowrite32(PCH_CMASK_RX_TX_SET, &priv->regs->ifregs[1].cmask); - iowrite32(0xffff, &priv->regs->ifregs[1].mask1); - iowrite32(0xffff, &priv->regs->ifregs[1].mask2); - iowrite32(0x0, &priv->regs->ifregs[1].id1); - iowrite32(0x0, &priv->regs->ifregs[1].id2); - iowrite32(0x0, &priv->regs->ifregs[1].mcont); - iowrite32(0x0, &priv->regs->ifregs[1].data[0]); - iowrite32(0x0, &priv->regs->ifregs[1].data[1]); - iowrite32(0x0, &priv->regs->ifregs[1].data[2]); - iowrite32(0x0, &priv->regs->ifregs[1].data[3]); - iowrite32(PCH_CMASK_RDWR | PCH_CMASK_MASK | - PCH_CMASK_ARB | PCH_CMASK_CTRL, - &priv->regs->ifregs[1].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[1].creq, i); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, i); } } @@ -389,7 +364,7 @@ static void pch_can_config_rx_tx_buffers(struct pch_can_priv *priv) for (i = PCH_RX_OBJ_START; i <= PCH_RX_OBJ_END; i++) { iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, i); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, i); iowrite32(0x0, &priv->regs->ifregs[0].id1); iowrite32(0x0, &priv->regs->ifregs[0].id2); @@ -403,6 +378,9 @@ static void pch_can_config_rx_tx_buffers(struct pch_can_priv *priv) /* In case FIFO mode, Last EoB of Rx Obj must be 1 */ if (i == PCH_RX_OBJ_END) pch_can_bit_set(&priv->regs->ifregs[0].mcont, + PCH_IF_MCONT_EOB); + else + pch_can_bit_clear(&priv->regs->ifregs[0].mcont, PCH_IF_MCONT_EOB); iowrite32(0, &priv->regs->ifregs[0].mask1); @@ -414,13 +392,13 @@ static void pch_can_config_rx_tx_buffers(struct pch_can_priv *priv) PCH_CMASK_ARB | PCH_CMASK_CTRL, &priv->regs->ifregs[0].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, i); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, i); } for (i = PCH_TX_OBJ_START; i <= PCH_TX_OBJ_END; i++) { iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[1].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[1].creq, i); + pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, i); /* Resetting DIR bit for reception */ iowrite32(0x0, &priv->regs->ifregs[1].id1); @@ -441,7 +419,7 @@ static void pch_can_config_rx_tx_buffers(struct pch_can_priv *priv) PCH_CMASK_ARB | PCH_CMASK_CTRL, &priv->regs->ifregs[1].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[1].creq, i); + pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, i); } } @@ -451,7 +429,7 @@ static void pch_can_init(struct pch_can_priv *priv) pch_can_set_run_mode(priv, PCH_CAN_STOP); /* Clearing all the message object buffers. */ - pch_can_clear_buffers(priv); + pch_can_clear_if_buffers(priv); /* Configuring the respective message object as either rx/tx object. */ pch_can_config_rx_tx_buffers(priv); @@ -496,7 +474,7 @@ static void pch_can_int_clr(struct pch_can_priv *priv, u32 mask) pch_can_bit_clear(&priv->regs->ifregs[0].mcont, PCH_IF_MCONT_NEWDAT | PCH_IF_MCONT_INTPND); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, mask); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, mask); } else if ((mask >= PCH_TX_OBJ_START) && (mask <= PCH_TX_OBJ_END)) { /* Setting CMASK for clearing interrupts for frame transmission. */ @@ -512,7 +490,7 @@ static void pch_can_int_clr(struct pch_can_priv *priv, u32 mask) pch_can_bit_clear(&priv->regs->ifregs[1].mcont, PCH_IF_MCONT_NEWDAT | PCH_IF_MCONT_INTPND | PCH_IF_MCONT_TXRQXT); - pch_can_check_if_busy(&priv->regs->ifregs[1].creq, mask); + pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, mask); } } @@ -637,7 +615,7 @@ static void pch_fifo_thresh(struct pch_can_priv *priv, int obj_id) /* Clearing NewDat & IntPnd */ pch_can_bit_clear(&priv->regs->ifregs[0].mcont, PCH_IF_MCONT_INTPND); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, obj_id); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, obj_id); } else if (obj_id > PCH_FIFO_THRESH) { pch_can_int_clr(priv, obj_id); } else if (obj_id == PCH_FIFO_THRESH) { @@ -659,7 +637,7 @@ static void pch_can_rx_msg_lost(struct net_device *ndev, int obj_id) PCH_IF_MCONT_MSGLOST); iowrite32(PCH_CMASK_RDWR | PCH_CMASK_CTRL, &priv->regs->ifregs[0].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, obj_id); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, obj_id); skb = alloc_can_err_skb(ndev, &cf); if (!skb) @@ -689,7 +667,7 @@ static int pch_can_rx_normal(struct net_device *ndev, u32 obj_num, int quota) do { /* Reading the messsage object from the Message RAM */ iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, obj_num); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, obj_num); /* Reading the MCONT register. */ reg = ioread32(&priv->regs->ifregs[0].mcont); @@ -758,7 +736,7 @@ static void pch_can_tx_complete(struct net_device *ndev, u32 int_stat) can_get_echo_skb(ndev, int_stat - PCH_RX_OBJ_END - 1); iowrite32(PCH_CMASK_RX_TX_GET | PCH_CMASK_CLRINTPND, &priv->regs->ifregs[1].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[1].creq, int_stat); + pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, int_stat); dlc = get_can_dlc(ioread32(&priv->regs->ifregs[1].mcont) & PCH_IF_MCONT_DLC); stats->tx_bytes += dlc; @@ -767,7 +745,7 @@ static void pch_can_tx_complete(struct net_device *ndev, u32 int_stat) netif_wake_queue(ndev); } -static int pch_can_rx_poll(struct napi_struct *napi, int quota) +static int pch_can_poll(struct napi_struct *napi, int quota) { struct net_device *ndev = napi->dev; struct pch_can_priv *priv = netdev_priv(ndev); @@ -832,10 +810,10 @@ static int pch_set_bittiming(struct net_device *ndev) brp = (bt->tq) / (1000000000/PCH_CAN_CLK) - 1; canbit = brp & PCH_MSK_BITT_BRP; - canbit |= (bt->sjw - 1) << PCH_BIT_SJW; - canbit |= (bt->phase_seg1 + bt->prop_seg - 1) << PCH_BIT_TSEG1; - canbit |= (bt->phase_seg2 - 1) << PCH_BIT_TSEG2; - bepe = (brp & PCH_MSK_BRPE_BRPE) >> PCH_BIT_BRPE_BRPE; + canbit |= (bt->sjw - 1) << PCH_BIT_SJW_SHIFT; + canbit |= (bt->phase_seg1 + bt->prop_seg - 1) << PCH_BIT_TSEG1_SHIFT; + canbit |= (bt->phase_seg2 - 1) << PCH_BIT_TSEG2_SHIFT; + bepe = (brp & PCH_MSK_BRPE_BRPE) >> PCH_BIT_BRPE_BRPE_SHIFT; iowrite32(canbit, &priv->regs->bitt); iowrite32(bepe, &priv->regs->brpe); pch_can_bit_clear(&priv->regs->cont, PCH_CTRL_CCE); @@ -947,7 +925,7 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev) { struct pch_can_priv *priv = netdev_priv(ndev); struct can_frame *cf = (struct can_frame *)skb->data; - int tx_buffer_avail = 0; + int tx_obj_no; int i; if (can_dropped_invalid_skb(ndev, skb)) @@ -957,16 +935,16 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev) if (ioread32(&priv->regs->treq2) & PCH_TREQ2_TX_MASK) netif_stop_queue(ndev); - tx_buffer_avail = priv->tx_obj; + tx_obj_no = priv->tx_obj; priv->tx_obj = PCH_TX_OBJ_START; } else { - tx_buffer_avail = priv->tx_obj; + tx_obj_no = priv->tx_obj; priv->tx_obj++; } /* Reading the Msg Obj from the Msg RAM to the Interface register. */ iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[1].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[1].creq, tx_buffer_avail); + pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, tx_obj_no); /* Setting the CMASK register. */ pch_can_bit_set(&priv->regs->ifregs[1].cmask, PCH_CMASK_ALL); @@ -995,7 +973,7 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev) &priv->regs->ifregs[1].data[i / 2]); } - can_put_echo_skb(skb, ndev, tx_buffer_avail - PCH_RX_OBJ_END - 1); + can_put_echo_skb(skb, ndev, tx_obj_no - PCH_RX_OBJ_END - 1); /* Updating the size of the data. */ pch_can_bit_clear(&priv->regs->ifregs[1].mcont, 0x0f); @@ -1010,7 +988,7 @@ static netdev_tx_t pch_xmit(struct sk_buff *skb, struct net_device *ndev) pch_can_bit_set(&priv->regs->ifregs[1].mcont, PCH_IF_MCONT_NEWDAT | PCH_IF_MCONT_TXRQXT); - pch_can_check_if_busy(&priv->regs->ifregs[1].creq, tx_buffer_avail); + pch_can_rw_msg_obj(&priv->regs->ifregs[1].creq, tx_obj_no); return NETDEV_TX_OK; } @@ -1064,7 +1042,7 @@ static u32 pch_can_get_rxtx_ir(struct pch_can_priv *priv, u32 buff_num, ie = PCH_IF_MCONT_TXIE; iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[dir].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[dir].creq, buff_num); + pch_can_rw_msg_obj(&priv->regs->ifregs[dir].creq, buff_num); if (((ioread32(&priv->regs->ifregs[dir].id2)) & PCH_ID_MSGVAL) && ((ioread32(&priv->regs->ifregs[dir].mcont)) & ie)) { @@ -1076,37 +1054,37 @@ static u32 pch_can_get_rxtx_ir(struct pch_can_priv *priv, u32 buff_num, } static void pch_can_set_rx_buffer_link(struct pch_can_priv *priv, - u32 buffer_num, u32 set) + u32 buffer_num, int set) { iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, buffer_num); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, buffer_num); iowrite32(PCH_CMASK_RDWR | PCH_CMASK_CTRL, &priv->regs->ifregs[0].cmask); - if (set == PCH_ENABLE) + if (set) pch_can_bit_clear(&priv->regs->ifregs[0].mcont, PCH_IF_MCONT_EOB); else pch_can_bit_set(&priv->regs->ifregs[0].mcont, PCH_IF_MCONT_EOB); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, buffer_num); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, buffer_num); } static void pch_can_get_rx_buffer_link(struct pch_can_priv *priv, u32 buffer_num, u32 *link) { iowrite32(PCH_CMASK_RX_TX_GET, &priv->regs->ifregs[0].cmask); - pch_can_check_if_busy(&priv->regs->ifregs[0].creq, buffer_num); + pch_can_rw_msg_obj(&priv->regs->ifregs[0].creq, buffer_num); if (ioread32(&priv->regs->ifregs[0].mcont) & PCH_IF_MCONT_EOB) - *link = PCH_DISABLE; + *link = 0; else - *link = PCH_ENABLE; + *link = 1; } static int pch_can_get_buffer_status(struct pch_can_priv *priv) { return (ioread32(&priv->regs->treq1) & 0xffff) | - ((ioread32(&priv->regs->treq2) & 0xffff) << 16); + (ioread32(&priv->regs->treq2) << 16); } static int pch_can_suspend(struct pci_dev *pdev, pm_message_t state) @@ -1114,7 +1092,7 @@ static int pch_can_suspend(struct pci_dev *pdev, pm_message_t state) int i; /* Counter variable. */ int retval; /* Return value. */ u32 buf_stat; /* Variable for reading the transmit buffer status. */ - u32 counter = 0xFFFFFF; + int counter = PCH_COUNTER_LIMIT; struct net_device *dev = pci_get_drvdata(pdev); struct pch_can_priv *priv = netdev_priv(dev); @@ -1291,7 +1269,7 @@ static int __devinit pch_can_probe(struct pci_dev *pdev, ndev->netdev_ops = &pch_can_netdev_ops; priv->can.clock.freq = PCH_CAN_CLK; /* Hz */ - netif_napi_add(ndev, &priv->napi, pch_can_rx_poll, PCH_RX_OBJ_END); + netif_napi_add(ndev, &priv->napi, pch_can_poll, PCH_RX_OBJ_END); rc = register_candev(ndev); if (rc) { -- 1.6.0.6 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/