i2c: xtensa s6000 i2c driver

Support for the s6000 on-chip i2c controller.

Signed-off-by: Oskar Schirmer <os@emlix.com>
Signed-off-by: Daniel Glöckner <dg@emlix.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>

1 files changed, 407 insertions, 0 deletions

diff --git a/drivers/i2c/busses/i2c-s6000.c b/drivers/i2c/busses/i2c-s6000.c
new file mode 100644
index 000000000000..c91359f4965c
--- /dev/null
+++ b/drivers/i2c/busses/i2c-s6000.c
@@ -0,0 +1,407 @@
+/*
+ * drivers/i2c/busses/i2c-s6000.c
+ *
+ * Description: Driver for S6000 Family I2C Interface
+ * Copyright (c) 2008 emlix GmbH
+ * Author:      Oskar Schirmer <os@emlix.com>
+ *
+ * Partially based on i2c-bfin-twi.c driver by <sonic.zhang@analog.com>
+ * Copyright (c) 2005-2007 Analog Devices, Inc.
+ *
+ * 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., 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <linux/clk.h>
+#include <linux/err.h>
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/i2c.h>
+#include <linux/i2c/s6000.h>
+#include <linux/timer.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/interrupt.h>
+#include <linux/platform_device.h>
+
+#include <asm/io.h>
+#include "i2c-s6000.h"
+
+#define DRV_NAME "i2c-s6000"
+
+#define POLL_TIMEOUT    (2 * HZ)
+
+struct s6i2c_if {
+        u8 __iomem              *reg; /* memory mapped registers */
+        int                     irq;
+        spinlock_t              lock;
+        struct i2c_msg          *msgs; /* messages currently handled */
+        int                     msgs_num; /* nb of msgs to do */
+        int                     msgs_push; /* nb of msgs read/written */
+        int                     msgs_done; /* nb of msgs finally handled */
+        unsigned                push; /* nb of bytes read/written in msg */
+        unsigned                done; /* nb of bytes finally handled */
+        int                     timeout_count; /* timeout retries left */
+        struct timer_list       timeout_timer;
+        struct i2c_adapter      adap;
+        struct completion       complete;
+        struct clk              *clk;
+        struct resource         *res;
+};
+
+static inline u16 i2c_rd16(struct s6i2c_if *iface, unsigned n)
+{
+        return readw(iface->reg + (n));
+}
+
+static inline void i2c_wr16(struct s6i2c_if *iface, unsigned n, u16 v)
+{
+        writew(v, iface->reg + (n));
+}
+
+static inline u32 i2c_rd32(struct s6i2c_if *iface, unsigned n)
+{
+        return readl(iface->reg + (n));
+}
+
+static inline void i2c_wr32(struct s6i2c_if *iface, unsigned n, u32 v)
+{
+        writel(v, iface->reg + (n));
+}
+
+static struct s6i2c_if s6i2c_if;
+
+static void s6i2c_handle_interrupt(struct s6i2c_if *iface)
+{
+        if (i2c_rd16(iface, S6_I2C_INTRSTAT) & (1 << S6_I2C_INTR_TXABRT)) {
+                i2c_rd16(iface, S6_I2C_CLRTXABRT);
+                i2c_wr16(iface, S6_I2C_INTRMASK, 0);
+                complete(&iface->complete);
+                return;
+        }
+        if (iface->msgs_done >= iface->msgs_num) {
+                dev_err(&iface->adap.dev, "s6i2c: spurious I2C irq: %04x\n",
+                        i2c_rd16(iface, S6_I2C_INTRSTAT));
+                i2c_wr16(iface, S6_I2C_INTRMASK, 0);
+                return;
+        }
+        while ((iface->msgs_push < iface->msgs_num)
+            && (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_TFNF))) {
+                struct i2c_msg *m = &iface->msgs[iface->msgs_push];
+                if (!(m->flags & I2C_M_RD))
+                        i2c_wr16(iface, S6_I2C_DATACMD, m->buf[iface->push]);
+                else
+                        i2c_wr16(iface, S6_I2C_DATACMD,
+                                 1 << S6_I2C_DATACMD_READ);
+                if (++iface->push >= m->len) {
+                        iface->push = 0;
+                        iface->msgs_push += 1;
+                }
+        }
+        do {
+                struct i2c_msg *m = &iface->msgs[iface->msgs_done];
+                if (!(m->flags & I2C_M_RD)) {
+                        if (iface->msgs_done < iface->msgs_push)
+                                iface->msgs_done += 1;
+                        else
+                                break;
+                } else if (i2c_rd16(iface, S6_I2C_STATUS)
+                                & (1 << S6_I2C_STATUS_RFNE)) {
+                        m->buf[iface->done] = i2c_rd16(iface, S6_I2C_DATACMD);
+                        if (++iface->done >= m->len) {
+                                iface->done = 0;
+                                iface->msgs_done += 1;
+                        }
+                } else{
+                        break;
+                }
+        } while (iface->msgs_done < iface->msgs_num);
+        if (iface->msgs_done >= iface->msgs_num) {
+                i2c_wr16(iface, S6_I2C_INTRMASK, 1 << S6_I2C_INTR_TXABRT);
+                complete(&iface->complete);
+        } else if (iface->msgs_push >= iface->msgs_num) {
+                i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXABRT) |
+                                                 (1 << S6_I2C_INTR_RXFULL));
+        } else {
+                i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXABRT) |
+                                                 (1 << S6_I2C_INTR_TXEMPTY) |
+                                                 (1 << S6_I2C_INTR_RXFULL));
+        }
+}
+
+static irqreturn_t s6i2c_interrupt_entry(int irq, void *dev_id)
+{
+        struct s6i2c_if *iface = dev_id;
+        if (!(i2c_rd16(iface, S6_I2C_STATUS) & ((1 << S6_I2C_INTR_RXUNDER)
+                                              | (1 << S6_I2C_INTR_RXOVER)
+                                              | (1 << S6_I2C_INTR_RXFULL)
+                                              | (1 << S6_I2C_INTR_TXOVER)
+                                              | (1 << S6_I2C_INTR_TXEMPTY)
+                                              | (1 << S6_I2C_INTR_RDREQ)
+                                              | (1 << S6_I2C_INTR_TXABRT)
+                                              | (1 << S6_I2C_INTR_RXDONE)
+                                              | (1 << S6_I2C_INTR_ACTIVITY)
+                                              | (1 << S6_I2C_INTR_STOPDET)
+                                              | (1 << S6_I2C_INTR_STARTDET)
+                                              | (1 << S6_I2C_INTR_GENCALL))))
+                return IRQ_NONE;
+
+        spin_lock(&iface->lock);
+        del_timer(&iface->timeout_timer);
+        s6i2c_handle_interrupt(iface);
+        spin_unlock(&iface->lock);
+        return IRQ_HANDLED;
+}
+
+static void s6i2c_timeout(unsigned long data)
+{
+        struct s6i2c_if *iface = (struct s6i2c_if *)data;
+        unsigned long flags;
+
+        spin_lock_irqsave(&iface->lock, flags);
+        s6i2c_handle_interrupt(iface);
+        if (--iface->timeout_count > 0) {
+                iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
+                add_timer(&iface->timeout_timer);
+        } else {
+                complete(&iface->complete);
+                i2c_wr16(iface, S6_I2C_INTRMASK, 0);
+        }
+        spin_unlock_irqrestore(&iface->lock, flags);
+}
+
+static int s6i2c_master_xfer(struct i2c_adapter *adap,
+                                struct i2c_msg *msgs, int num)
+{
+        struct s6i2c_if *iface = adap->algo_data;
+        int i;
+        if (num == 0)
+                return 0;
+        if (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_ACTIVITY))
+                yield();
+        i2c_wr16(iface, S6_I2C_INTRMASK, 0);
+        i2c_rd16(iface, S6_I2C_CLRINTR);
+        for (i = 0; i < num; i++) {
+                if (msgs[i].flags & I2C_M_TEN) {
+                        dev_err(&adap->dev,
+                                "s6i2c: 10 bits addr not supported\n");
+                        return -EINVAL;
+                }
+                if (msgs[i].len == 0) {
+                        dev_err(&adap->dev,
+                                "s6i2c: zero length message not supported\n");
+                        return -EINVAL;
+                }
+                if (msgs[i].addr != msgs[0].addr) {
+                        dev_err(&adap->dev,
+                                "s6i2c: multiple xfer cannot change target\n");
+                        return -EINVAL;
+                }
+        }
+
+        iface->msgs = msgs;
+        iface->msgs_num = num;
+        iface->msgs_push = 0;
+        iface->msgs_done = 0;
+        iface->push = 0;
+        iface->done = 0;
+        iface->timeout_count = 10;
+        i2c_wr16(iface, S6_I2C_TAR, msgs[0].addr);
+        i2c_wr16(iface, S6_I2C_ENABLE, 1);
+        i2c_wr16(iface, S6_I2C_INTRMASK, (1 << S6_I2C_INTR_TXEMPTY) |
+                                         (1 << S6_I2C_INTR_TXABRT));
+
+        iface->timeout_timer.expires = jiffies + POLL_TIMEOUT;
+        add_timer(&iface->timeout_timer);
+        wait_for_completion(&iface->complete);
+        del_timer_sync(&iface->timeout_timer);
+        while (i2c_rd32(iface, S6_I2C_TXFLR) > 0)
+                schedule();
+        while (i2c_rd16(iface, S6_I2C_STATUS) & (1 << S6_I2C_STATUS_ACTIVITY))
+                schedule();
+
+        i2c_wr16(iface, S6_I2C_INTRMASK, 0);
+        i2c_wr16(iface, S6_I2C_ENABLE, 0);
+        return iface->msgs_done;
+}
+
+static u32 s6i2c_functionality(struct i2c_adapter *adap)
+{
+        return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+static struct i2c_algorithm s6i2c_algorithm = {
+        .master_xfer   = s6i2c_master_xfer,
+        .functionality = s6i2c_functionality,
+};
+
+static u16 __devinit nanoseconds_on_clk(struct s6i2c_if *iface, u32 ns)
+{
+        u32 dividend = ((clk_get_rate(iface->clk) / 1000) * ns) / 1000000;
+        if (dividend > 0xffff)
+                return 0xffff;
+        return dividend;
+}
+
+static int __devinit s6i2c_probe(struct platform_device *dev)
+{
+        struct s6i2c_if *iface = &s6i2c_if;
+        struct i2c_adapter *p_adap;
+        const char *clock;
+        int bus_num, rc;
+        spin_lock_init(&iface->lock);
+        init_completion(&iface->complete);
+        iface->irq = platform_get_irq(dev, 0);
+        if (iface->irq < 0) {
+                rc = iface->irq;
+                goto err_out;
+        }
+        iface->res = platform_get_resource(dev, IORESOURCE_MEM, 0);
+        if (!iface->res) {
+                rc = -ENXIO;
+                goto err_out;
+        }
+        iface->res = request_mem_region(iface->res->start,
+                                        resource_size(iface->res),
+                                        dev->dev.bus_id);
+        if (!iface->res) {
+                rc = -EBUSY;
+                goto err_out;
+        }
+        iface->reg = ioremap_nocache(iface->res->start,
+                                     resource_size(iface->res));
+        if (!iface->reg) {
+                rc = -ENOMEM;
+                goto err_reg;
+        }
+
+        clock = 0;
+        bus_num = -1;
+        if (dev->dev.platform_data) {
+                struct s6_i2c_platform_data *pdata = dev->dev.platform_data;
+                bus_num = pdata->bus_num;
+                clock = pdata->clock;
+        }
+        iface->clk = clk_get(&dev->dev, clock);
+        if (IS_ERR(iface->clk)) {
+                rc = PTR_ERR(iface->clk);
+                goto err_map;
+        }
+        rc = clk_enable(iface->clk);
+        if (rc < 0)
+                goto err_clk_put;
+        init_timer(&iface->timeout_timer);
+        iface->timeout_timer.function = s6i2c_timeout;
+        iface->timeout_timer.data = (unsigned long)iface;
+
+        p_adap = &iface->adap;
+        strlcpy(p_adap->name, dev->name, sizeof(p_adap->name));
+        p_adap->algo = &s6i2c_algorithm;
+        p_adap->algo_data = iface;
+        p_adap->nr = bus_num;
+        p_adap->class = 0;
+        p_adap->dev.parent = &dev->dev;
+        i2c_wr16(iface, S6_I2C_INTRMASK, 0);
+        rc = request_irq(iface->irq, s6i2c_interrupt_entry,
+                         IRQF_SHARED, dev->name, iface);
+        if (rc) {
+                dev_err(&p_adap->dev, "s6i2c: cant get IRQ %d\n", iface->irq);
+                goto err_clk_dis;
+        }
+
+        i2c_wr16(iface, S6_I2C_ENABLE, 0);
+        udelay(1);
+        i2c_wr32(iface, S6_I2C_SRESET, 1 << S6_I2C_SRESET_IC_SRST);
+        i2c_wr16(iface, S6_I2C_CLRTXABRT, 1);
+        i2c_wr16(iface, S6_I2C_CON,
+                        (1 << S6_I2C_CON_MASTER) |
+                        (S6_I2C_CON_SPEED_NORMAL << S6_I2C_CON_SPEED) |
+                        (0 << S6_I2C_CON_10BITSLAVE) |
+                        (0 << S6_I2C_CON_10BITMASTER) |
+                        (1 << S6_I2C_CON_RESTARTENA) |
+                        (1 << S6_I2C_CON_SLAVEDISABLE));
+        i2c_wr16(iface, S6_I2C_SSHCNT, nanoseconds_on_clk(iface, 4000));
+        i2c_wr16(iface, S6_I2C_SSLCNT, nanoseconds_on_clk(iface, 4700));
+        i2c_wr16(iface, S6_I2C_FSHCNT, nanoseconds_on_clk(iface, 600));
+        i2c_wr16(iface, S6_I2C_FSLCNT, nanoseconds_on_clk(iface, 1300));
+        i2c_wr16(iface, S6_I2C_RXTL, 0);
+        i2c_wr16(iface, S6_I2C_TXTL, 0);
+
+        platform_set_drvdata(dev, iface);
+        if (bus_num < 0)
+                rc = i2c_add_adapter(p_adap);
+        else
+                rc = i2c_add_numbered_adapter(p_adap);
+        if (rc)
+                goto err_irq_free;
+        return 0;
+
+err_irq_free:
+        free_irq(iface->irq, iface);
+err_clk_dis:
+        clk_disable(iface->clk);
+err_clk_put:
+        clk_put(iface->clk);
+err_map:
+        iounmap(iface->reg);
+err_reg:
+        release_mem_region(iface->res->start,
+                           resource_size(iface->res));
+err_out:
+        return rc;
+}
+
+static int __devexit s6i2c_remove(struct platform_device *pdev)
+{
+        struct s6i2c_if *iface = platform_get_drvdata(pdev);
+        i2c_wr16(iface, S6_I2C_ENABLE, 0);
+        platform_set_drvdata(pdev, NULL);
+        i2c_del_adapter(&iface->adap);
+        free_irq(iface->irq, iface);
+        clk_disable(iface->clk);
+        clk_put(iface->clk);
+        iounmap(iface->reg);
+        release_mem_region(iface->res->start,
+                           resource_size(iface->res));
+        return 0;
+}
+
+static struct platform_driver s6i2c_driver = {
+        .probe          = s6i2c_probe,
+        .remove         = __devexit_p(s6i2c_remove),
+        .driver         = {
+                .name   = DRV_NAME,
+                .owner  = THIS_MODULE,
+        },
+};
+
+static int __init s6i2c_init(void)
+{
+        pr_info("I2C: S6000 I2C driver\n");
+        return platform_driver_register(&s6i2c_driver);
+}
+
+static void __exit s6i2c_exit(void)
+{
+        platform_driver_unregister(&s6i2c_driver);
+}
+
+MODULE_DESCRIPTION("I2C-Bus adapter routines for S6000 I2C");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("platform:" DRV_NAME);
+
+subsys_initcall(s6i2c_init);
+module_exit(s6i2c_exit);