ensure that transmit and receive buffers are cache-line aligned invalidate cache for each packet as received update receive buffer descriptors one cache line at a time flush cache before transmitting Original patch by Marek: http://lists.denx.de/pipermail/u-boot/2012-February/117695.html

Signed-off-by: Eric Nelson eric.nelson@boundarydevices.com

--- V2 addresses some concerns from the ML: - Use readl()/writel() instead of mapped data structure accesses - Wrong comment style - &rbd_base[0] == rbd_base removed 'volatile' from fec_send().

V3 updates from ML (and Marek): consolidated CONFIG_FEC_DATA_ALIGNMENT and CONFIG_FEC_DESC_ALIGNMENT added cache flushes after initialization of TBD/RBD

drivers/net/fec_mxc.c | 265 +++++++++++++++++++++++++++++++++++-------------- drivers/net/fec_mxc.h | 19 +---- 2 files changed, 189 insertions(+), 95 deletions(-)

diff --git a/drivers/net/fec_mxc.c b/drivers/net/fec_mxc.c index 1fdd071..94a3927 100644 --- a/drivers/net/fec_mxc.c +++ b/drivers/net/fec_mxc.c @@ -50,6 +50,24 @@ DECLARE_GLOBAL_DATA_PTR; #define CONFIG_FEC_MXC_SWAP_PACKET #endif

+#if ARCH_DMA_MINALIGN > CONFIG_SYS_CACHELINE_SIZE +#define CONFIG_FEC_ALIGN ARCH_DMA_MINALIGN +#else +#define CONFIG_FEC_ALIGN CONFIG_SYS_CACHELINE_SIZE +#endif + +#define RXDESC_PER_CACHELINE (CONFIG_FEC_ALIGN/sizeof(struct fec_bd)) + +/* Check various alignment issues at compile time */ +#if ((CONFIG_FEC_ALIGN < 16) || (CONFIG_FEC_ALIGN % 16 != 0)) +#error "CONFIG_FEC_ALIGN must be multiple of 16!" +#endif + +#if ((PKTALIGN < CONFIG_FEC_ALIGN) || \ + (PKTALIGN % CONFIG_FEC_ALIGN != 0)) +#error "PKTALIGN must be multiple of CONFIG_FEC_ALIGN!" +#endif + #undef DEBUG

struct nbuf { @@ -259,43 +277,52 @@ static int fec_tx_task_disable(struct fec_priv *fec) * Initialize receive task's buffer descriptors * @param[in] fec all we know about the device yet * @param[in] count receive buffer count to be allocated - * @param[in] size size of each receive buffer + * @param[in] dsize desired size of each receive buffer * @return 0 on success * * For this task we need additional memory for the data buffers. And each * data buffer requires some alignment. Thy must be aligned to a specific - * boundary each (DB_DATA_ALIGNMENT). + * boundary each. */ -static int fec_rbd_init(struct fec_priv *fec, int count, int size) +static int fec_rbd_init(struct fec_priv *fec, int count, int dsize) { - int ix; - uint32_t p = 0; - - /* reserve data memory and consider alignment */ - if (fec->rdb_ptr == NULL) - fec->rdb_ptr = malloc(size * count + DB_DATA_ALIGNMENT); - p = (uint32_t)fec->rdb_ptr; - if (!p) { - puts("fec_mxc: not enough malloc memory\n"); - return -ENOMEM; - } - memset((void *)p, 0, size * count + DB_DATA_ALIGNMENT); - p += DB_DATA_ALIGNMENT-1; - p &= ~(DB_DATA_ALIGNMENT-1); - - for (ix = 0; ix < count; ix++) { - writel(p, &fec->rbd_base[ix].data_pointer); - p += size; - writew(FEC_RBD_EMPTY, &fec->rbd_base[ix].status); - writew(0, &fec->rbd_base[ix].data_length); - } + uint32_t size; + int i; + /* - * mark the last RBD to close the ring + * Allocate memory for the buffers. This allocation respects the + * alignment */ - writew(FEC_RBD_WRAP | FEC_RBD_EMPTY, &fec->rbd_base[ix - 1].status); + size = roundup(dsize, CONFIG_FEC_ALIGN); + for (i = 0; i < count; i++) { + uint32_t data_ptr = readl(&fec->rbd_base[i].data_pointer); + if (data_ptr == 0) { + uint8_t *data = memalign(CONFIG_FEC_ALIGN, + size); + if (!data) { + printf("%s: error allocating rxbuf %d\n", + __func__, i); + goto err; + } + writel((uint32_t)data, &fec->rbd_base[i].data_pointer); + } /* needs allocation */ + writew(FEC_RBD_EMPTY, &fec->rbd_base[i].status); + writew(0, &fec->rbd_base[i].data_length); + } + + /* Mark the last RBD to close the ring. */ + writew(FEC_RBD_WRAP | FEC_RBD_EMPTY, &fec->rbd_base[i - 1].status); fec->rbd_index = 0;

return 0; + +err: + for (; i >= 0; i--) { + uint32_t data_ptr = readl(&fec->rbd_base[i].data_pointer); + free((void *)data_ptr); + } + + return -ENOMEM; }

/** @@ -312,9 +339,13 @@ static int fec_rbd_init(struct fec_priv *fec, int count, int size) */ static void fec_tbd_init(struct fec_priv *fec) { + unsigned addr = (unsigned)fec->tbd_base; + unsigned size = roundup(2 * sizeof(struct fec_bd), + CONFIG_FEC_ALIGN); writew(0x0000, &fec->tbd_base[0].status); writew(FEC_TBD_WRAP, &fec->tbd_base[1].status); fec->tbd_index = 0; + flush_dcache_range(addr, addr+size); }

/** @@ -324,16 +355,10 @@ static void fec_tbd_init(struct fec_priv *fec) */ static void fec_rbd_clean(int last, struct fec_bd *pRbd) { - /* - * Reset buffer descriptor as empty - */ + unsigned short flags = FEC_RBD_EMPTY; if (last) - writew(FEC_RBD_WRAP | FEC_RBD_EMPTY, &pRbd->status); - else - writew(FEC_RBD_EMPTY, &pRbd->status); - /* - * no data in it - */ + flags |= FEC_RBD_WRAP; + writew(flags, &pRbd->status); writew(0, &pRbd->data_length); }

@@ -387,12 +412,25 @@ static int fec_open(struct eth_device *edev) { struct fec_priv *fec = (struct fec_priv *)edev->priv; int speed; + uint32_t addr, size; + int i;

debug("fec_open: fec_open(dev)\n"); /* full-duplex, heartbeat disabled */ writel(1 << 2, &fec->eth->x_cntrl); fec->rbd_index = 0;

+ /* Invalidate all descriptors */ + for (i = 0; i < FEC_RBD_NUM - 1; i++) + fec_rbd_clean(0, &fec->rbd_base[i]); + fec_rbd_clean(1, &fec->rbd_base[i]); + + /* Flush the descriptors into RAM */ + size = roundup(FEC_RBD_NUM * sizeof(struct fec_bd), + CONFIG_FEC_ALIGN); + addr = (uint32_t)fec->rbd_base; + flush_dcache_range(addr, addr + size); + #ifdef FEC_QUIRK_ENET_MAC /* Enable ENET HW endian SWAP */ writel(readl(&fec->eth->ecntrl) | FEC_ECNTRL_DBSWAP, @@ -478,38 +516,55 @@ static int fec_open(struct eth_device *edev)

static int fec_init(struct eth_device *dev, bd_t* bd) { - uint32_t base; struct fec_priv *fec = (struct fec_priv *)dev->priv; uint32_t mib_ptr = (uint32_t)&fec->eth->rmon_t_drop; uint32_t rcntrl; - int i; + uint32_t size; + int i, ret;

/* Initialize MAC address */ fec_set_hwaddr(dev);

/* - * reserve memory for both buffer descriptor chains at once - * Datasheet forces the startaddress of each chain is 16 byte - * aligned + * Allocate transmit descriptors, there are two in total. This + * allocation respects cache alignment. */ - if (fec->base_ptr == NULL) - fec->base_ptr = malloc((2 + FEC_RBD_NUM) * - sizeof(struct fec_bd) + DB_ALIGNMENT); - base = (uint32_t)fec->base_ptr; - if (!base) { - puts("fec_mxc: not enough malloc memory\n"); - return -ENOMEM; + if (!fec->tbd_base) { + size = roundup(2 * sizeof(struct fec_bd), + CONFIG_FEC_ALIGN); + fec->tbd_base = memalign(CONFIG_FEC_ALIGN, size); + if (!fec->tbd_base) { + ret = -ENOMEM; + goto err1; + } + memset(fec->tbd_base, 0, size); + fec_tbd_init(fec); + flush_dcache_range((unsigned)fec->tbd_base, size); } - memset((void *)base, 0, (2 + FEC_RBD_NUM) * - sizeof(struct fec_bd) + DB_ALIGNMENT); - base += (DB_ALIGNMENT-1); - base &= ~(DB_ALIGNMENT-1); - - fec->rbd_base = (struct fec_bd *)base;

- base += FEC_RBD_NUM * sizeof(struct fec_bd); - - fec->tbd_base = (struct fec_bd *)base; + /* + * Allocate receive descriptors. This allocation respects cache + * alignment. + */ + if (!fec->rbd_base) { + size = roundup(FEC_RBD_NUM * sizeof(struct fec_bd), + CONFIG_FEC_ALIGN); + fec->rbd_base = memalign(CONFIG_FEC_ALIGN, size); + if (!fec->rbd_base) { + ret = -ENOMEM; + goto err2; + } + memset(fec->rbd_base, 0, size); + /* + * Initialize RxBD ring + */ + if (fec_rbd_init(fec, FEC_RBD_NUM, FEC_MAX_PKT_SIZE) < 0) { + ret = -ENOMEM; + goto err3; + } + flush_dcache_range((unsigned)fec->rbd_base, + (unsigned)fec->rbd_base + size); + }

/* * Set interrupt mask register @@ -566,23 +621,19 @@ static int fec_init(struct eth_device *dev, bd_t* bd) writel((uint32_t)fec->tbd_base, &fec->eth->etdsr); writel((uint32_t)fec->rbd_base, &fec->eth->erdsr);

- /* - * Initialize RxBD/TxBD rings - */ - if (fec_rbd_init(fec, FEC_RBD_NUM, FEC_MAX_PKT_SIZE) < 0) { - free(fec->base_ptr); - fec->base_ptr = NULL; - return -ENOMEM; - } - fec_tbd_init(fec); - - #ifndef CONFIG_PHYLIB if (fec->xcv_type != SEVENWIRE) miiphy_restart_aneg(dev); #endif fec_open(dev); return 0; + +err3: + free(fec->rbd_base); +err2: + free(fec->tbd_base); +err1: + return ret; }

/** @@ -631,9 +682,11 @@ static void fec_halt(struct eth_device *dev) * @param[in] length Data count in bytes * @return 0 on success */ -static int fec_send(struct eth_device *dev, volatile void* packet, int length) +static int fec_send(struct eth_device *dev, void *packet, int length) { unsigned int status; + uint32_t size; + uint32_t addr;

/* * This routine transmits one frame. This routine only accepts @@ -650,15 +703,21 @@ static int fec_send(struct eth_device *dev, volatile void* packet, int length) }

/* - * Setup the transmit buffer - * Note: We are always using the first buffer for transmission, - * the second will be empty and only used to stop the DMA engine + * Setup the transmit buffer. We are always using the first buffer for + * transmission, the second will be empty and only used to stop the DMA + * engine. We also flush the packet to RAM here to avoid cache trouble. */ #ifdef CONFIG_FEC_MXC_SWAP_PACKET swap_packet((uint32_t *)packet, length); #endif + + addr = (uint32_t)packet; + size = roundup(length, CONFIG_FEC_ALIGN); + flush_dcache_range(addr, addr + size); + writew(length, &fec->tbd_base[fec->tbd_index].data_length); - writel((uint32_t)packet, &fec->tbd_base[fec->tbd_index].data_pointer); + writel(addr, &fec->tbd_base[fec->tbd_index].data_pointer); + /* * update BD's status now * This block: @@ -672,16 +731,30 @@ static int fec_send(struct eth_device *dev, volatile void* packet, int length) writew(status, &fec->tbd_base[fec->tbd_index].status);

/* + * Flush data cache. This code flushes both TX descriptors to RAM. + * After this code, the descriptors will be safely in RAM and we + * can start DMA. + */ + size = roundup(2 * sizeof(struct fec_bd), CONFIG_FEC_ALIGN); + addr = (uint32_t)fec->tbd_base; + flush_dcache_range(addr, addr + size); + + /* * Enable SmartDMA transmit task */ fec_tx_task_enable(fec);

/* - * wait until frame is sent . + * Wait until frame is sent. On each turn of the wait cycle, we must + * invalidate data cache to see what's really in RAM. Also, we need + * barrier here. */ + invalidate_dcache_range(addr, addr + size); while (readw(&fec->tbd_base[fec->tbd_index].status) & FEC_TBD_READY) { udelay(1); + invalidate_dcache_range(addr, addr + size); } + debug("fec_send: status 0x%x index %d\n", readw(&fec->tbd_base[fec->tbd_index].status), fec->tbd_index); @@ -707,6 +780,8 @@ static int fec_recv(struct eth_device *dev) int frame_length, len = 0; struct nbuf *frame; uint16_t bd_status; + uint32_t addr, size; + int i; uchar buff[FEC_MAX_PKT_SIZE];

/* @@ -737,8 +812,23 @@ static int fec_recv(struct eth_device *dev) }

/* - * ensure reading the right buffer status + * Read the buffer status. Before the status can be read, the data cache + * must be invalidated, because the data in RAM might have been changed + * by DMA. The descriptors are properly aligned to cachelines so there's + * no need to worry they'd overlap. + * + * WARNING: By invalidating the descriptor here, we also invalidate + * the descriptors surrounding this one. Therefore we can NOT change the + * contents of this descriptor nor the surrounding ones. The problem is + * that in order to mark the descriptor as processed, we need to change + * the descriptor. The solution is to mark the whole cache line when all + * descriptors in the cache line are processed. */ + addr = (uint32_t)rbd; + addr &= ~(CONFIG_FEC_ALIGN - 1); + size = roundup(sizeof(struct fec_bd), CONFIG_FEC_ALIGN); + invalidate_dcache_range(addr, addr + size); + bd_status = readw(&rbd->status); debug("fec_recv: status 0x%x\n", bd_status);

@@ -751,6 +841,13 @@ static int fec_recv(struct eth_device *dev) frame = (struct nbuf *)readl(&rbd->data_pointer); frame_length = readw(&rbd->data_length) - 4; /* + * Invalidate data cache over the buffer + */ + addr = (uint32_t)frame; + size = roundup(frame_length, CONFIG_FEC_ALIGN); + invalidate_dcache_range(addr, addr + size); + + /* * Fill the buffer and pass it to upper layers */ #ifdef CONFIG_FEC_MXC_SWAP_PACKET @@ -765,11 +862,25 @@ static int fec_recv(struct eth_device *dev) (ulong)rbd->data_pointer, bd_status); } + /* - * free the current buffer, restart the engine - * and move forward to the next buffer + * Free the current buffer, restart the engine and move forward + * to the next buffer. Here we check if the whole cacheline of + * descriptors was already processed and if so, we mark it free + * as whole. */ - fec_rbd_clean(fec->rbd_index == (FEC_RBD_NUM - 1) ? 1 : 0, rbd); + size = RXDESC_PER_CACHELINE - 1; + if ((fec->rbd_index & size) == size) { + i = fec->rbd_index - size; + addr = (uint32_t)&fec->rbd_base[i]; + for (; i <= fec->rbd_index ; i++) { + fec_rbd_clean(i == (FEC_RBD_NUM - 1), + &fec->rbd_base[i]); + } + flush_dcache_range(addr, + addr + CONFIG_FEC_ALIGN); + } + fec_rx_task_enable(fec); fec->rbd_index = (fec->rbd_index + 1) % FEC_RBD_NUM; } diff --git a/drivers/net/fec_mxc.h b/drivers/net/fec_mxc.h index 2eb7803..852b2e0 100644 --- a/drivers/net/fec_mxc.h +++ b/drivers/net/fec_mxc.h @@ -234,22 +234,6 @@ struct ethernet_regs { #endif

/** - * @brief Descriptor buffer alignment - * - * i.MX27 requires a 16 byte alignment (but for the first element only) - */ -#define DB_ALIGNMENT 16 - -/** - * @brief Data buffer alignment - * - * i.MX27 requires a four byte alignment for transmit and 16 bits - * alignment for receive so take 16 - * Note: Valid for member data_pointer in struct buffer_descriptor - */ -#define DB_DATA_ALIGNMENT 16 - -/** * @brief Receive & Transmit Buffer Descriptor definitions * * Note: The first BD must be aligned (see DB_ALIGNMENT) @@ -282,8 +266,7 @@ struct fec_priv { struct fec_bd *tbd_base; /* TBD ring */ int tbd_index; /* next transmit BD to write */ bd_t *bd; - void *rdb_ptr; - void *base_ptr; + uint8_t *tdb_ptr; int dev_id; int phy_id; struct mii_dev *bus;