ptp: Added a clock driver for the IXP46x.

This patch adds a driver for the hardware time stamping unit found on the
IXP465. The basic clock operations and an external trigger are implemented.

Signed-off-by: Richard Cochran <richard.cochran@omicron.at>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: John Stultz <john.stultz@linaro.org>
Acked-by: Krzysztof Halasa <khc@pm.waw.pl>
Signed-off-by: John Stultz <john.stultz@linaro.org>

3 files changed, 346 insertions, 0 deletions

diff --git a/drivers/ptp/Kconfig b/drivers/ptp/Kconfig
index 12eb8447c26b..fcfafd091fdd 100644
--- a/drivers/ptp/Kconfig
+++ b/drivers/ptp/Kconfig
@@ -40,4 +40,17 @@ config PTP_1588_CLOCK_GIANFAR
           To compile this driver as a module, choose M here: the module
           will be called gianfar_ptp.
 
+config PTP_1588_CLOCK_IXP46X
+        tristate "Intel IXP46x as PTP clock"
+        depends on PTP_1588_CLOCK
+        depends on IXP4XX_ETH
+        help
+          This driver adds support for using the IXP46X as a PTP
+          clock. This clock is only useful if your PTP programs are
+          getting hardware time stamps on the PTP Ethernet packets
+          using the SO_TIMESTAMPING API.
+
+          To compile this driver as a module, choose M here: the module
+          will be called ptp_ixp46x.
+
 endmenu
diff --git a/drivers/ptp/Makefile b/drivers/ptp/Makefile
index 480e2afdc999..f6933e83de72 100644
--- a/drivers/ptp/Makefile
+++ b/drivers/ptp/Makefile
@@ -4,3 +4,4 @@
 
 ptp-y                                   := ptp_clock.o ptp_chardev.o ptp_sysfs.o
 obj-$(CONFIG_PTP_1588_CLOCK)            += ptp.o
+obj-$(CONFIG_PTP_1588_CLOCK_IXP46X)     += ptp_ixp46x.o
diff --git a/drivers/ptp/ptp_ixp46x.c b/drivers/ptp/ptp_ixp46x.c
new file mode 100644
index 000000000000..803d665b15ef
--- /dev/null
+++ b/drivers/ptp/ptp_ixp46x.c
@@ -0,0 +1,332 @@
+/*
+ * PTP 1588 clock using the IXP46X
+ *
+ * Copyright (C) 2010 OMICRON electronics GmbH
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program; if not, write to the Free Software
+ *  Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+#include <linux/device.h>
+#include <linux/err.h>
+#include <linux/gpio.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+#include <linux/irq.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#include <linux/ptp_clock_kernel.h>
+#include <mach/ixp46x_ts.h>
+
+#define DRIVER          "ptp_ixp46x"
+#define N_EXT_TS        2
+#define MASTER_GPIO     8
+#define MASTER_IRQ      25
+#define SLAVE_GPIO      7
+#define SLAVE_IRQ       24
+
+struct ixp_clock {
+        struct ixp46x_ts_regs *regs;
+        struct ptp_clock *ptp_clock;
+        struct ptp_clock_info caps;
+        int exts0_enabled;
+        int exts1_enabled;
+};
+
+DEFINE_SPINLOCK(register_lock);
+
+/*
+ * Register access functions
+ */
+
+static u64 ixp_systime_read(struct ixp46x_ts_regs *regs)
+{
+        u64 ns;
+        u32 lo, hi;
+
+        lo = __raw_readl(&regs->systime_lo);
+        hi = __raw_readl(&regs->systime_hi);
+
+        ns = ((u64) hi) << 32;
+        ns |= lo;
+        ns <<= TICKS_NS_SHIFT;
+
+        return ns;
+}
+
+static void ixp_systime_write(struct ixp46x_ts_regs *regs, u64 ns)
+{
+        u32 hi, lo;
+
+        ns >>= TICKS_NS_SHIFT;
+        hi = ns >> 32;
+        lo = ns & 0xffffffff;
+
+        __raw_writel(lo, &regs->systime_lo);
+        __raw_writel(hi, &regs->systime_hi);
+}
+
+/*
+ * Interrupt service routine
+ */
+
+static irqreturn_t isr(int irq, void *priv)
+{
+        struct ixp_clock *ixp_clock = priv;
+        struct ixp46x_ts_regs *regs = ixp_clock->regs;
+        struct ptp_clock_event event;
+        u32 ack = 0, lo, hi, val;
+
+        val = __raw_readl(&regs->event);
+
+        if (val & TSER_SNS) {
+                ack |= TSER_SNS;
+                if (ixp_clock->exts0_enabled) {
+                        hi = __raw_readl(&regs->asms_hi);
+                        lo = __raw_readl(&regs->asms_lo);
+                        event.type = PTP_CLOCK_EXTTS;
+                        event.index = 0;
+                        event.timestamp = ((u64) hi) << 32;
+                        event.timestamp |= lo;
+                        event.timestamp <<= TICKS_NS_SHIFT;
+                        ptp_clock_event(ixp_clock->ptp_clock, &event);
+                }
+        }
+
+        if (val & TSER_SNM) {
+                ack |= TSER_SNM;
+                if (ixp_clock->exts1_enabled) {
+                        hi = __raw_readl(&regs->amms_hi);
+                        lo = __raw_readl(&regs->amms_lo);
+                        event.type = PTP_CLOCK_EXTTS;
+                        event.index = 1;
+                        event.timestamp = ((u64) hi) << 32;
+                        event.timestamp |= lo;
+                        event.timestamp <<= TICKS_NS_SHIFT;
+                        ptp_clock_event(ixp_clock->ptp_clock, &event);
+                }
+        }
+
+        if (val & TTIPEND)
+                ack |= TTIPEND; /* this bit seems to be always set */
+
+        if (ack) {
+                __raw_writel(ack, &regs->event);
+                return IRQ_HANDLED;
+        } else
+                return IRQ_NONE;
+}
+
+/*
+ * PTP clock operations
+ */
+
+static int ptp_ixp_adjfreq(struct ptp_clock_info *ptp, s32 ppb)
+{
+        u64 adj;
+        u32 diff, addend;
+        int neg_adj = 0;
+        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
+        struct ixp46x_ts_regs *regs = ixp_clock->regs;
+
+        if (ppb < 0) {
+                neg_adj = 1;
+                ppb = -ppb;
+        }
+        addend = DEFAULT_ADDEND;
+        adj = addend;
+        adj *= ppb;
+        diff = div_u64(adj, 1000000000ULL);
+
+        addend = neg_adj ? addend - diff : addend + diff;
+
+        __raw_writel(addend, &regs->addend);
+
+        return 0;
+}
+
+static int ptp_ixp_adjtime(struct ptp_clock_info *ptp, s64 delta)
+{
+        s64 now;
+        unsigned long flags;
+        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
+        struct ixp46x_ts_regs *regs = ixp_clock->regs;
+
+        spin_lock_irqsave(&register_lock, flags);
+
+        now = ixp_systime_read(regs);
+        now += delta;
+        ixp_systime_write(regs, now);
+
+        spin_unlock_irqrestore(&register_lock, flags);
+
+        return 0;
+}
+
+static int ptp_ixp_gettime(struct ptp_clock_info *ptp, struct timespec *ts)
+{
+        u64 ns;
+        u32 remainder;
+        unsigned long flags;
+        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
+        struct ixp46x_ts_regs *regs = ixp_clock->regs;
+
+        spin_lock_irqsave(&register_lock, flags);
+
+        ns = ixp_systime_read(regs);
+
+        spin_unlock_irqrestore(&register_lock, flags);
+
+        ts->tv_sec = div_u64_rem(ns, 1000000000, &remainder);
+        ts->tv_nsec = remainder;
+        return 0;
+}
+
+static int ptp_ixp_settime(struct ptp_clock_info *ptp,
+                           const struct timespec *ts)
+{
+        u64 ns;
+        unsigned long flags;
+        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
+        struct ixp46x_ts_regs *regs = ixp_clock->regs;
+
+        ns = ts->tv_sec * 1000000000ULL;
+        ns += ts->tv_nsec;
+
+        spin_lock_irqsave(&register_lock, flags);
+
+        ixp_systime_write(regs, ns);
+
+        spin_unlock_irqrestore(&register_lock, flags);
+
+        return 0;
+}
+
+static int ptp_ixp_enable(struct ptp_clock_info *ptp,
+                          struct ptp_clock_request *rq, int on)
+{
+        struct ixp_clock *ixp_clock = container_of(ptp, struct ixp_clock, caps);
+
+        switch (rq->type) {
+        case PTP_CLK_REQ_EXTTS:
+                switch (rq->extts.index) {
+                case 0:
+                        ixp_clock->exts0_enabled = on ? 1 : 0;
+                        break;
+                case 1:
+                        ixp_clock->exts1_enabled = on ? 1 : 0;
+                        break;
+                default:
+                        return -EINVAL;
+                }
+                return 0;
+        default:
+                break;
+        }
+
+        return -EOPNOTSUPP;
+}
+
+static struct ptp_clock_info ptp_ixp_caps = {
+        .owner          = THIS_MODULE,
+        .name           = "IXP46X timer",
+        .max_adj        = 66666655,
+        .n_ext_ts       = N_EXT_TS,
+        .pps            = 0,
+        .adjfreq        = ptp_ixp_adjfreq,
+        .adjtime        = ptp_ixp_adjtime,
+        .gettime        = ptp_ixp_gettime,
+        .settime        = ptp_ixp_settime,
+        .enable         = ptp_ixp_enable,
+};
+
+/* module operations */
+
+static struct ixp_clock ixp_clock;
+
+static int setup_interrupt(int gpio)
+{
+        int irq;
+
+        gpio_line_config(gpio, IXP4XX_GPIO_IN);
+
+        irq = gpio_to_irq(gpio);
+
+        if (NO_IRQ == irq)
+                return NO_IRQ;
+
+        if (irq_set_irq_type(irq, IRQF_TRIGGER_FALLING)) {
+                pr_err("cannot set trigger type for irq %d\n", irq);
+                return NO_IRQ;
+        }
+
+        if (request_irq(irq, isr, 0, DRIVER, &ixp_clock)) {
+                pr_err("request_irq failed for irq %d\n", irq);
+                return NO_IRQ;
+        }
+
+        return irq;
+}
+
+static void __exit ptp_ixp_exit(void)
+{
+        free_irq(MASTER_IRQ, &ixp_clock);
+        free_irq(SLAVE_IRQ, &ixp_clock);
+        ptp_clock_unregister(ixp_clock.ptp_clock);
+}
+
+static int __init ptp_ixp_init(void)
+{
+        if (!cpu_is_ixp46x())
+                return -ENODEV;
+
+        ixp_clock.regs =
+                (struct ixp46x_ts_regs __iomem *) IXP4XX_TIMESYNC_BASE_VIRT;
+
+        ixp_clock.caps = ptp_ixp_caps;
+
+        ixp_clock.ptp_clock = ptp_clock_register(&ixp_clock.caps);
+
+        if (IS_ERR(ixp_clock.ptp_clock))
+                return PTR_ERR(ixp_clock.ptp_clock);
+
+        __raw_writel(DEFAULT_ADDEND, &ixp_clock.regs->addend);
+        __raw_writel(1, &ixp_clock.regs->trgt_lo);
+        __raw_writel(0, &ixp_clock.regs->trgt_hi);
+        __raw_writel(TTIPEND, &ixp_clock.regs->event);
+
+        if (MASTER_IRQ != setup_interrupt(MASTER_GPIO)) {
+                pr_err("failed to setup gpio %d as irq\n", MASTER_GPIO);
+                goto no_master;
+        }
+        if (SLAVE_IRQ != setup_interrupt(SLAVE_GPIO)) {
+                pr_err("failed to setup gpio %d as irq\n", SLAVE_GPIO);
+                goto no_slave;
+        }
+
+        return 0;
+no_slave:
+        free_irq(MASTER_IRQ, &ixp_clock);
+no_master:
+        ptp_clock_unregister(ixp_clock.ptp_clock);
+        return -ENODEV;
+}
+
+module_init(ptp_ixp_init);
+module_exit(ptp_ixp_exit);
+
+MODULE_AUTHOR("Richard Cochran <richard.cochran@omicron.at>");
+MODULE_DESCRIPTION("PTP clock using the IXP46X timer");
+MODULE_LICENSE("GPL");