]> git.baikalelectronics.ru Git - uboot.git/commitdiff
net: add support for bcm6348-enet
authorÁlvaro Fernández Rojas <noltari@gmail.com>
Sat, 1 Dec 2018 18:00:24 +0000 (19:00 +0100)
committerDaniel Schwierzeck <daniel.schwierzeck@gmail.com>
Wed, 19 Dec 2018 14:23:00 +0000 (15:23 +0100)
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
Reviewed-by: Daniel Schwierzeck <daniel.schwierzeck@gmail.com>
drivers/net/Kconfig
drivers/net/Makefile
drivers/net/bcm6348-eth.c [new file with mode: 0644]
include/configs/bmips_common.h

index 8fb365fc5d2a64165dff2a4f003499f73759e68a..2b7cec8804b390916f14512228828df91d8bc74a 100644 (file)
@@ -72,6 +72,16 @@ config BCM_SF2_ETH_GMAC
          by the BCM_SF2_ETH driver.
          Say Y to any bcmcygnus based platforms.
 
+config BCM6348_ETH
+       bool "BCM6348 EMAC support"
+       depends on DM_ETH && ARCH_BMIPS
+       select DMA
+       select DMA_CHANNELS
+       select MII
+       select PHYLIB
+       help
+         This driver supports the BCM6348 Ethernet MAC.
+
 config DWC_ETH_QOS
        bool "Synopsys DWC Ethernet QOS device support"
        depends on DM_ETH
index 99056aa041d08e3fd959d5bdcfbf6a713a7cb795..2647d4dd2315f6cb354a69b891106bc8cdfc9ace 100644 (file)
@@ -6,6 +6,7 @@
 obj-$(CONFIG_ALTERA_TSE) += altera_tse.o
 obj-$(CONFIG_AG7XXX) += ag7xxx.o
 obj-$(CONFIG_ARMADA100_FEC) += armada100_fec.o
+obj-$(CONFIG_BCM6348_ETH) += bcm6348-eth.o
 obj-$(CONFIG_DRIVER_AT91EMAC) += at91_emac.o
 obj-$(CONFIG_DRIVER_AX88180) += ax88180.o
 obj-$(CONFIG_BCM_SF2_ETH) += bcm-sf2-eth.o
diff --git a/drivers/net/bcm6348-eth.c b/drivers/net/bcm6348-eth.c
new file mode 100644 (file)
index 0000000..7100e68
--- /dev/null
@@ -0,0 +1,537 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2018 Álvaro Fernández Rojas <noltari@gmail.com>
+ *
+ * Derived from linux/drivers/net/ethernet/broadcom/bcm63xx_enet.c:
+ *     Copyright (C) 2008 Maxime Bizon <mbizon@freebox.fr>
+ */
+
+#include <common.h>
+#include <clk.h>
+#include <dm.h>
+#include <dma.h>
+#include <miiphy.h>
+#include <net.h>
+#include <phy.h>
+#include <reset.h>
+#include <wait_bit.h>
+#include <asm/io.h>
+
+#define ETH_RX_DESC                    PKTBUFSRX
+#define ETH_MAX_MTU_SIZE               1518
+#define ETH_TIMEOUT                    100
+#define ETH_TX_WATERMARK               32
+
+/* ETH Receiver Configuration register */
+#define ETH_RXCFG_REG                  0x00
+#define ETH_RXCFG_ENFLOW_SHIFT         5
+#define ETH_RXCFG_ENFLOW_MASK          (1 << ETH_RXCFG_ENFLOW_SHIFT)
+
+/* ETH Receive Maximum Length register */
+#define ETH_RXMAXLEN_REG               0x04
+#define ETH_RXMAXLEN_SHIFT             0
+#define ETH_RXMAXLEN_MASK              (0x7ff << ETH_RXMAXLEN_SHIFT)
+
+/* ETH Transmit Maximum Length register */
+#define ETH_TXMAXLEN_REG               0x08
+#define ETH_TXMAXLEN_SHIFT             0
+#define ETH_TXMAXLEN_MASK              (0x7ff << ETH_TXMAXLEN_SHIFT)
+
+/* MII Status/Control register */
+#define MII_SC_REG                     0x10
+#define MII_SC_MDCFREQDIV_SHIFT                0
+#define MII_SC_MDCFREQDIV_MASK         (0x7f << MII_SC_MDCFREQDIV_SHIFT)
+#define MII_SC_PREAMBLE_EN_SHIFT       7
+#define MII_SC_PREAMBLE_EN_MASK                (1 << MII_SC_PREAMBLE_EN_SHIFT)
+
+/* MII Data register */
+#define MII_DAT_REG                    0x14
+#define MII_DAT_DATA_SHIFT             0
+#define MII_DAT_DATA_MASK              (0xffff << MII_DAT_DATA_SHIFT)
+#define MII_DAT_TA_SHIFT               16
+#define MII_DAT_TA_MASK                        (0x3 << MII_DAT_TA_SHIFT)
+#define MII_DAT_REG_SHIFT              18
+#define MII_DAT_REG_MASK               (0x1f << MII_DAT_REG_SHIFT)
+#define MII_DAT_PHY_SHIFT              23
+#define MII_DAT_PHY_MASK               (0x1f << MII_DAT_PHY_SHIFT)
+#define MII_DAT_OP_SHIFT               28
+#define MII_DAT_OP_WRITE               (0x5 << MII_DAT_OP_SHIFT)
+#define MII_DAT_OP_READ                        (0x6 << MII_DAT_OP_SHIFT)
+
+/* ETH Interrupts Mask register */
+#define ETH_IRMASK_REG                 0x18
+
+/* ETH Interrupts register */
+#define ETH_IR_REG                     0x1c
+#define ETH_IR_MII_SHIFT               0
+#define ETH_IR_MII_MASK                        (1 << ETH_IR_MII_SHIFT)
+
+/* ETH Control register */
+#define ETH_CTL_REG                    0x2c
+#define ETH_CTL_ENABLE_SHIFT           0
+#define ETH_CTL_ENABLE_MASK            (1 << ETH_CTL_ENABLE_SHIFT)
+#define ETH_CTL_DISABLE_SHIFT          1
+#define ETH_CTL_DISABLE_MASK           (1 << ETH_CTL_DISABLE_SHIFT)
+#define ETH_CTL_RESET_SHIFT            2
+#define ETH_CTL_RESET_MASK             (1 << ETH_CTL_RESET_SHIFT)
+#define ETH_CTL_EPHY_SHIFT             3
+#define ETH_CTL_EPHY_MASK              (1 << ETH_CTL_EPHY_SHIFT)
+
+/* ETH Transmit Control register */
+#define ETH_TXCTL_REG                  0x30
+#define ETH_TXCTL_FD_SHIFT             0
+#define ETH_TXCTL_FD_MASK              (1 << ETH_TXCTL_FD_SHIFT)
+
+/* ETH Transmit Watermask register */
+#define ETH_TXWMARK_REG                        0x34
+#define ETH_TXWMARK_WM_SHIFT           0
+#define ETH_TXWMARK_WM_MASK            (0x3f << ETH_TXWMARK_WM_SHIFT)
+
+/* MIB Control register */
+#define MIB_CTL_REG                    0x38
+#define MIB_CTL_RDCLEAR_SHIFT          0
+#define MIB_CTL_RDCLEAR_MASK           (1 << MIB_CTL_RDCLEAR_SHIFT)
+
+/* ETH Perfect Match registers */
+#define ETH_PM_CNT                     4
+#define ETH_PML_REG(x)                 (0x58 + (x) * 0x8)
+#define ETH_PMH_REG(x)                 (0x5c + (x) * 0x8)
+#define ETH_PMH_VALID_SHIFT            16
+#define ETH_PMH_VALID_MASK             (1 << ETH_PMH_VALID_SHIFT)
+
+/* MIB Counters registers */
+#define MIB_REG_CNT                    55
+#define MIB_REG(x)                     (0x200 + (x) * 4)
+
+/* ETH data */
+struct bcm6348_eth_priv {
+       void __iomem *base;
+       /* DMA */
+       struct dma rx_dma;
+       struct dma tx_dma;
+       /* PHY */
+       int phy_id;
+       struct phy_device *phy_dev;
+};
+
+static void bcm6348_eth_mac_disable(struct bcm6348_eth_priv *priv)
+{
+       /* disable emac */
+       clrsetbits_be32(priv->base + ETH_CTL_REG, ETH_CTL_ENABLE_MASK,
+                       ETH_CTL_DISABLE_MASK);
+
+       /* wait until emac is disabled */
+       if (wait_for_bit_be32(priv->base + ETH_CTL_REG,
+                             ETH_CTL_DISABLE_MASK, false,
+                             ETH_TIMEOUT, false))
+               pr_err("%s: error disabling emac\n", __func__);
+}
+
+static void bcm6348_eth_mac_enable(struct bcm6348_eth_priv *priv)
+{
+       setbits_be32(priv->base + ETH_CTL_REG, ETH_CTL_ENABLE_MASK);
+}
+
+static void bcm6348_eth_mac_reset(struct bcm6348_eth_priv *priv)
+{
+       /* reset emac */
+       writel_be(ETH_CTL_RESET_MASK, priv->base + ETH_CTL_REG);
+       wmb();
+
+       /* wait until emac is reset */
+       if (wait_for_bit_be32(priv->base + ETH_CTL_REG,
+                             ETH_CTL_RESET_MASK, false,
+                             ETH_TIMEOUT, false))
+               pr_err("%s: error resetting emac\n", __func__);
+}
+
+static int bcm6348_eth_free_pkt(struct udevice *dev, uchar *packet, int len)
+{
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+
+       return dma_prepare_rcv_buf(&priv->rx_dma, packet, len);
+}
+
+static int bcm6348_eth_recv(struct udevice *dev, int flags, uchar **packetp)
+{
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+
+       return dma_receive(&priv->rx_dma, (void**)packetp, NULL);
+}
+
+static int bcm6348_eth_send(struct udevice *dev, void *packet, int length)
+{
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+
+       return dma_send(&priv->tx_dma, packet, length, NULL);
+}
+
+static int bcm6348_eth_adjust_link(struct udevice *dev,
+                                  struct phy_device *phydev)
+{
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+
+       /* mac duplex parameters */
+       if (phydev->duplex)
+               setbits_be32(priv->base + ETH_TXCTL_REG, ETH_TXCTL_FD_MASK);
+       else
+               clrbits_be32(priv->base + ETH_TXCTL_REG, ETH_TXCTL_FD_MASK);
+
+       /* rx flow control (pause frame handling) */
+       if (phydev->pause)
+               setbits_be32(priv->base + ETH_RXCFG_REG,
+                            ETH_RXCFG_ENFLOW_MASK);
+       else
+               clrbits_be32(priv->base + ETH_RXCFG_REG,
+                            ETH_RXCFG_ENFLOW_MASK);
+
+       return 0;
+}
+
+static int bcm6348_eth_start(struct udevice *dev)
+{
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+       int ret, i;
+
+       /* prepare rx dma buffers */
+       for (i = 0; i < ETH_RX_DESC; i++) {
+               ret = dma_prepare_rcv_buf(&priv->rx_dma, net_rx_packets[i],
+                                         PKTSIZE_ALIGN);
+               if (ret < 0)
+                       break;
+       }
+
+       /* enable dma rx channel */
+       dma_enable(&priv->rx_dma);
+
+       /* enable dma tx channel */
+       dma_enable(&priv->tx_dma);
+
+       ret = phy_startup(priv->phy_dev);
+       if (ret) {
+               pr_err("%s: could not initialize phy\n", __func__);
+               return ret;
+       }
+
+       if (!priv->phy_dev->link) {
+               pr_err("%s: no phy link\n", __func__);
+               return -EIO;
+       }
+
+       bcm6348_eth_adjust_link(dev, priv->phy_dev);
+
+       /* zero mib counters */
+       for (i = 0; i < MIB_REG_CNT; i++)
+               writel_be(0, MIB_REG(i));
+
+       /* enable rx flow control */
+       setbits_be32(priv->base + ETH_RXCFG_REG, ETH_RXCFG_ENFLOW_MASK);
+
+       /* set max rx/tx length */
+       writel_be((ETH_MAX_MTU_SIZE << ETH_RXMAXLEN_SHIFT) &
+                 ETH_RXMAXLEN_MASK, priv->base + ETH_RXMAXLEN_REG);
+       writel_be((ETH_MAX_MTU_SIZE << ETH_TXMAXLEN_SHIFT) &
+                 ETH_TXMAXLEN_MASK, priv->base + ETH_TXMAXLEN_REG);
+
+       /* set correct transmit fifo watermark */
+       writel_be((ETH_TX_WATERMARK << ETH_TXWMARK_WM_SHIFT) &
+                 ETH_TXWMARK_WM_MASK, priv->base + ETH_TXWMARK_REG);
+
+       /* enable emac */
+       bcm6348_eth_mac_enable(priv);
+
+       /* clear interrupts */
+       writel_be(0, priv->base + ETH_IRMASK_REG);
+
+       return 0;
+}
+
+static void bcm6348_eth_stop(struct udevice *dev)
+{
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+
+       /* disable dma rx channel */
+       dma_disable(&priv->rx_dma);
+
+       /* disable dma tx channel */
+       dma_disable(&priv->tx_dma);
+
+       /* disable emac */
+       bcm6348_eth_mac_disable(priv);
+}
+
+static int bcm6348_eth_write_hwaddr(struct udevice *dev)
+{
+       struct eth_pdata *pdata = dev_get_platdata(dev);
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+       bool running = false;
+
+       /* check if emac is running */
+       if (readl_be(priv->base + ETH_CTL_REG) & ETH_CTL_ENABLE_MASK)
+               running = true;
+
+       /* disable emac */
+       if (running)
+               bcm6348_eth_mac_disable(priv);
+
+       /* set mac address */
+       writel_be((pdata->enetaddr[2] << 24) | (pdata->enetaddr[3]) << 16 |
+                 (pdata->enetaddr[4]) << 8 | (pdata->enetaddr[5]),
+                 priv->base + ETH_PML_REG(0));
+       writel_be((pdata->enetaddr[1]) | (pdata->enetaddr[0] << 8) |
+                 ETH_PMH_VALID_MASK, priv->base + ETH_PMH_REG(0));
+
+       /* enable emac */
+       if (running)
+               bcm6348_eth_mac_enable(priv);
+
+       return 0;
+}
+
+static const struct eth_ops bcm6348_eth_ops = {
+       .free_pkt = bcm6348_eth_free_pkt,
+       .recv = bcm6348_eth_recv,
+       .send = bcm6348_eth_send,
+       .start = bcm6348_eth_start,
+       .stop = bcm6348_eth_stop,
+       .write_hwaddr = bcm6348_eth_write_hwaddr,
+};
+
+static const struct udevice_id bcm6348_eth_ids[] = {
+       { .compatible = "brcm,bcm6348-enet", },
+       { /* sentinel */ }
+};
+
+static int bcm6348_mdio_op(void __iomem *base, uint32_t data)
+{
+       /* make sure mii interrupt status is cleared */
+       writel_be(ETH_IR_MII_MASK, base + ETH_IR_REG);
+
+       /* issue mii op */
+       writel_be(data, base + MII_DAT_REG);
+
+       /* wait until emac is disabled */
+       return wait_for_bit_be32(base + ETH_IR_REG,
+                                ETH_IR_MII_MASK, true,
+                                ETH_TIMEOUT, false);
+}
+
+static int bcm6348_mdio_read(struct mii_dev *bus, int addr, int devaddr,
+                            int reg)
+{
+       void __iomem *base = bus->priv;
+       uint32_t val;
+
+       val = MII_DAT_OP_READ;
+       val |= (reg << MII_DAT_REG_SHIFT) & MII_DAT_REG_MASK;
+       val |= (0x2 << MII_DAT_TA_SHIFT) & MII_DAT_TA_MASK;
+       val |= (addr << MII_DAT_PHY_SHIFT) & MII_DAT_PHY_MASK;
+
+       if (bcm6348_mdio_op(base, val)) {
+               pr_err("%s: timeout\n", __func__);
+               return -EINVAL;
+       }
+
+       val = readl_be(base + MII_DAT_REG) & MII_DAT_DATA_MASK;
+       val >>= MII_DAT_DATA_SHIFT;
+
+       return val;
+}
+
+static int bcm6348_mdio_write(struct mii_dev *bus, int addr, int dev_addr,
+                             int reg, u16 value)
+{
+       void __iomem *base = bus->priv;
+       uint32_t val;
+
+       val = MII_DAT_OP_WRITE;
+       val |= (reg << MII_DAT_REG_SHIFT) & MII_DAT_REG_MASK;
+       val |= (0x2 << MII_DAT_TA_SHIFT) & MII_DAT_TA_MASK;
+       val |= (addr << MII_DAT_PHY_SHIFT) & MII_DAT_PHY_MASK;
+       val |= (value << MII_DAT_DATA_SHIFT) & MII_DAT_DATA_MASK;
+
+       if (bcm6348_mdio_op(base, val)) {
+               pr_err("%s: timeout\n", __func__);
+               return -EINVAL;
+       }
+
+       return 0;
+}
+
+static int bcm6348_mdio_init(const char *name, void __iomem *base)
+{
+       struct mii_dev *bus;
+
+       bus = mdio_alloc();
+       if (!bus) {
+               pr_err("%s: failed to allocate MDIO bus\n", __func__);
+               return -ENOMEM;
+       }
+
+       bus->read = bcm6348_mdio_read;
+       bus->write = bcm6348_mdio_write;
+       bus->priv = base;
+       snprintf(bus->name, sizeof(bus->name), "%s", name);
+
+       return mdio_register(bus);
+}
+
+static int bcm6348_phy_init(struct udevice *dev)
+{
+       struct eth_pdata *pdata = dev_get_platdata(dev);
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+       struct mii_dev *bus;
+
+       /* get mii bus */
+       bus = miiphy_get_dev_by_name(dev->name);
+
+       /* phy connect */
+       priv->phy_dev = phy_connect(bus, priv->phy_id, dev,
+                                   pdata->phy_interface);
+       if (!priv->phy_dev) {
+               pr_err("%s: no phy device\n", __func__);
+               return -ENODEV;
+       }
+
+       priv->phy_dev->supported = (SUPPORTED_10baseT_Half |
+                                   SUPPORTED_10baseT_Full |
+                                   SUPPORTED_100baseT_Half |
+                                   SUPPORTED_100baseT_Full |
+                                   SUPPORTED_Autoneg |
+                                   SUPPORTED_Pause |
+                                   SUPPORTED_MII);
+       priv->phy_dev->advertising = priv->phy_dev->supported;
+
+       /* phy config */
+       phy_config(priv->phy_dev);
+
+       return 0;
+}
+
+static int bcm6348_eth_probe(struct udevice *dev)
+{
+       struct eth_pdata *pdata = dev_get_platdata(dev);
+       struct bcm6348_eth_priv *priv = dev_get_priv(dev);
+       struct ofnode_phandle_args phy;
+       const char *phy_mode;
+       int ret, i;
+
+       /* get base address */
+       priv->base = dev_remap_addr(dev);
+       if (!priv->base)
+               return -EINVAL;
+       pdata->iobase = (phys_addr_t) priv->base;
+
+       /* get phy mode */
+       pdata->phy_interface = PHY_INTERFACE_MODE_NONE;
+       phy_mode = dev_read_string(dev, "phy-mode");
+       if (phy_mode)
+               pdata->phy_interface = phy_get_interface_by_name(phy_mode);
+       if (pdata->phy_interface == PHY_INTERFACE_MODE_NONE)
+               return -ENODEV;
+
+       /* get phy */
+       if (dev_read_phandle_with_args(dev, "phy", NULL, 0, 0, &phy))
+               return -ENOENT;
+       priv->phy_id = ofnode_read_u32_default(phy.node, "reg", -1);
+
+       /* get dma channels */
+       ret = dma_get_by_name(dev, "tx", &priv->tx_dma);
+       if (ret)
+               return -EINVAL;
+
+       ret = dma_get_by_name(dev, "rx", &priv->rx_dma);
+       if (ret)
+               return -EINVAL;
+
+       /* try to enable clocks */
+       for (i = 0; ; i++) {
+               struct clk clk;
+               int ret;
+
+               ret = clk_get_by_index(dev, i, &clk);
+               if (ret < 0)
+                       break;
+
+               ret = clk_enable(&clk);
+               if (ret < 0) {
+                       pr_err("%s: error enabling clock %d\n", __func__, i);
+                       return ret;
+               }
+
+               ret = clk_free(&clk);
+               if (ret < 0) {
+                       pr_err("%s: error freeing clock %d\n", __func__, i);
+                       return ret;
+               }
+       }
+
+       /* try to perform resets */
+       for (i = 0; ; i++) {
+               struct reset_ctl reset;
+               int ret;
+
+               ret = reset_get_by_index(dev, i, &reset);
+               if (ret < 0)
+                       break;
+
+               ret = reset_deassert(&reset);
+               if (ret < 0) {
+                       pr_err("%s: error deasserting reset %d\n", __func__, i);
+                       return ret;
+               }
+
+               ret = reset_free(&reset);
+               if (ret < 0) {
+                       pr_err("%s: error freeing reset %d\n", __func__, i);
+                       return ret;
+               }
+       }
+
+       /* disable emac */
+       bcm6348_eth_mac_disable(priv);
+
+       /* reset emac */
+       bcm6348_eth_mac_reset(priv);
+
+       /* select correct mii interface */
+       if (pdata->phy_interface == PHY_INTERFACE_MODE_INTERNAL)
+               clrbits_be32(priv->base + ETH_CTL_REG, ETH_CTL_EPHY_MASK);
+       else
+               setbits_be32(priv->base + ETH_CTL_REG, ETH_CTL_EPHY_MASK);
+
+       /* turn on mdc clock */
+       writel_be((0x1f << MII_SC_MDCFREQDIV_SHIFT) |
+                 MII_SC_PREAMBLE_EN_MASK, priv->base + MII_SC_REG);
+
+       /* set mib counters to not clear when read */
+       clrbits_be32(priv->base + MIB_CTL_REG, MIB_CTL_RDCLEAR_MASK);
+
+       /* initialize perfect match registers */
+       for (i = 0; i < ETH_PM_CNT; i++) {
+               writel_be(0, priv->base + ETH_PML_REG(i));
+               writel_be(0, priv->base + ETH_PMH_REG(i));
+       }
+
+       /* init mii bus */
+       ret = bcm6348_mdio_init(dev->name, priv->base);
+       if (ret)
+               return ret;
+
+       /* init phy */
+       ret = bcm6348_phy_init(dev);
+       if (ret)
+               return ret;
+
+       return 0;
+}
+
+U_BOOT_DRIVER(bcm6348_eth) = {
+       .name = "bcm6348_eth",
+       .id = UCLASS_ETH,
+       .of_match = bcm6348_eth_ids,
+       .ops = &bcm6348_eth_ops,
+       .platdata_auto_alloc_size = sizeof(struct eth_pdata),
+       .priv_auto_alloc_size = sizeof(struct bcm6348_eth_priv),
+       .probe = bcm6348_eth_probe,
+};
index 39ca2e0bf3f5ff57cb415b40e7b68aecef4bc97f..788f4af70dab9d61bd70bf89eb6814d05503caf2 100644 (file)
@@ -6,6 +6,10 @@
 #ifndef __CONFIG_BMIPS_COMMON_H
 #define __CONFIG_BMIPS_COMMON_H
 
+/* ETH */
+#define CONFIG_PHY_RESET_DELAY         20
+#define CONFIG_SYS_RX_ETH_BUFFER       6
+
 /* UART */
 #define CONFIG_SYS_BAUDRATE_TABLE      { 9600, 19200, 38400, 57600, 115200, \
                                          230400, 500000, 1500000 }
@@ -16,7 +20,7 @@
 
 /* Memory usage */
 #define CONFIG_SYS_MAXARGS             24
-#define CONFIG_SYS_MALLOC_LEN          (1024 * 1024)
+#define CONFIG_SYS_MALLOC_LEN          (2 * 1024 * 1024)
 #define CONFIG_SYS_BOOTPARAMS_LEN      (128 * 1024)
 #define CONFIG_SYS_CBSIZE              512