diff options
Diffstat (limited to 'drivers/net/wan/ixp4xx_hss.c')
| -rw-r--r-- | drivers/net/wan/ixp4xx_hss.c | 95 |
1 files changed, 91 insertions, 4 deletions
diff --git a/drivers/net/wan/ixp4xx_hss.c b/drivers/net/wan/ixp4xx_hss.c index bb719b6114c..c705046d861 100644 --- a/drivers/net/wan/ixp4xx_hss.c +++ b/drivers/net/wan/ixp4xx_hss.c @@ -166,6 +166,29 @@ #define CLK46X_SPEED_4096KHZ (( 16 << 22) | (280 << 12) | 1023) #define CLK46X_SPEED_8192KHZ (( 8 << 22) | (280 << 12) | 2047) +/* + * HSS_CONFIG_CLOCK_CR register consists of 3 parts: + * A (10 bits), B (10 bits) and C (12 bits). + * IXP42x HSS clock generator operation (verified with an oscilloscope): + * Each clock bit takes 7.5 ns (1 / 133.xx MHz). + * The clock sequence consists of (C - B) states of 0s and 1s, each state is + * A bits wide. It's followed by (B + 1) states of 0s and 1s, each state is + * (A + 1) bits wide. + * + * The resulting average clock frequency (assuming 33.333 MHz oscillator) is: + * freq = 66.666 MHz / (A + (B + 1) / (C + 1)) + * minumum freq = 66.666 MHz / (A + 1) + * maximum freq = 66.666 MHz / A + * + * Example: A = 2, B = 2, C = 7, CLOCK_CR register = 2 << 22 | 2 << 12 | 7 + * freq = 66.666 MHz / (2 + (2 + 1) / (7 + 1)) = 28.07 MHz (Mb/s). + * The clock sequence is: 1100110011 (5 doubles) 000111000 (3 triples). + * The sequence takes (C - B) * A + (B + 1) * (A + 1) = 5 * 2 + 3 * 3 bits + * = 19 bits (each 7.5 ns long) = 142.5 ns (then the sequence repeats). + * The sequence consists of 4 complete clock periods, thus the average + * frequency (= clock rate) is 4 / 142.5 ns = 28.07 MHz (Mb/s). + * (max specified clock rate for IXP42x HSS is 8.192 Mb/s). + */ /* hss_config, LUT entries */ #define TDMMAP_UNASSIGNED 0 @@ -239,6 +262,7 @@ struct port { unsigned int clock_type, clock_rate, loopback; unsigned int initialized, carrier; u8 hdlc_cfg; + u32 clock_reg; }; /* NPE message structure */ @@ -393,7 +417,7 @@ static void hss_config(struct port *port) msg.cmd = PORT_CONFIG_WRITE; msg.hss_port = port->id; msg.index = HSS_CONFIG_CLOCK_CR; - msg.data32 = CLK42X_SPEED_2048KHZ /* FIXME */; + msg.data32 = port->clock_reg; hss_npe_send(port, &msg, "HSS_SET_CLOCK_CR"); memset(&msg, 0, sizeof(msg)); @@ -1160,6 +1184,62 @@ static int hss_hdlc_attach(struct net_device *dev, unsigned short encoding, } } +static u32 check_clock(u32 rate, u32 a, u32 b, u32 c, + u32 *best, u32 *best_diff, u32 *reg) +{ + /* a is 10-bit, b is 10-bit, c is 12-bit */ + u64 new_rate; + u32 new_diff; + + new_rate = ixp4xx_timer_freq * (u64)(c + 1); + do_div(new_rate, a * (c + 1) + b + 1); + new_diff = abs((u32)new_rate - rate); + + if (new_diff < *best_diff) { + *best = new_rate; + *best_diff = new_diff; + *reg = (a << 22) | (b << 12) | c; + } + return new_diff; +} + +static void find_best_clock(u32 rate, u32 *best, u32 *reg) +{ + u32 a, b, diff = 0xFFFFFFFF; + + a = ixp4xx_timer_freq / rate; + + if (a > 0x3FF) { /* 10-bit value - we can go as slow as ca. 65 kb/s */ + check_clock(rate, 0x3FF, 1, 1, best, &diff, reg); + return; + } + if (a == 0) { /* > 66.666 MHz */ + a = 1; /* minimum divider is 1 (a = 0, b = 1, c = 1) */ + rate = ixp4xx_timer_freq; + } + + if (rate * a == ixp4xx_timer_freq) { /* don't divide by 0 later */ + check_clock(rate, a - 1, 1, 1, best, &diff, reg); + return; + } + + for (b = 0; b < 0x400; b++) { + u64 c = (b + 1) * (u64)rate; + do_div(c, ixp4xx_timer_freq - rate * a); + c--; + if (c >= 0xFFF) { /* 12-bit - no need to check more 'b's */ + if (b == 0 && /* also try a bit higher rate */ + !check_clock(rate, a - 1, 1, 1, best, &diff, reg)) + return; + check_clock(rate, a, b, 0xFFF, best, &diff, reg); + return; + } + if (!check_clock(rate, a, b, c, best, &diff, reg)) + return; + if (!check_clock(rate, a, b, c + 1, best, &diff, reg)) + return; + } +} static int hss_hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) { @@ -1182,7 +1262,7 @@ static int hss_hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) } memset(&new_line, 0, sizeof(new_line)); new_line.clock_type = port->clock_type; - new_line.clock_rate = 2048000; /* FIXME */ + new_line.clock_rate = port->clock_rate; new_line.loopback = port->loopback; if (copy_to_user(line, &new_line, size)) return -EFAULT; @@ -1206,7 +1286,13 @@ static int hss_hdlc_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) return -EINVAL; port->clock_type = clk; /* Update settings */ - /* FIXME port->clock_rate = new_line.clock_rate */; + if (clk == CLOCK_INT) + find_best_clock(new_line.clock_rate, &port->clock_rate, + &port->clock_reg); + else { + port->clock_rate = 0; + port->clock_reg = CLK42X_SPEED_2048KHZ; + } port->loopback = new_line.loopback; spin_lock_irqsave(&npe_lock, flags); @@ -1266,7 +1352,8 @@ static int __devinit hss_init_one(struct platform_device *pdev) dev->netdev_ops = &hss_hdlc_ops; dev->tx_queue_len = 100; port->clock_type = CLOCK_EXT; - port->clock_rate = 2048000; + port->clock_rate = 0; + port->clock_reg = CLK42X_SPEED_2048KHZ; port->id = pdev->id; port->dev = &pdev->dev; port->plat = pdev->dev.platform_data; |