[PATCH] 2/5 powerpc: Rework PowerMac i2c part 2

This is the continuation of the previous patch. This one removes the old
PowerMac i2c drivers (i2c-keywest and i2c-pmac-smu) and replaces them
both with a single stub driver that uses the new PowerMac low i2c layer.

Now that i2c-keywest is gone, the low-i2c code is extended to support
interrupt driver transfers. All i2c busses now appear as platform
devices. Compatibility with existing drivers should be maintained as the
i2c bus names have been kept identical, except for the SMU bus but in
that later case, all users has been fixed.

With that patch added, matching a device node to an i2c_adapter becomes
trivial.

Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 246 insertions, 72 deletions

diff --git a/arch/powerpc/platforms/powermac/low_i2c.c b/arch/powerpc/platforms/powermac/low_i2c.c
index f31d6a678b9..a25e447f907 100644
--- a/arch/powerpc/platforms/powermac/low_i2c.c
+++ b/arch/powerpc/platforms/powermac/low_i2c.c
@@ -39,6 +39,10 @@
 #include <linux/pmu.h>
 #include <linux/delay.h>
 #include <linux/completion.h>
+#include <linux/platform_device.h>
+#include <linux/interrupt.h>
+#include <linux/completion.h>
+#include <linux/timer.h>
 #include <asm/keylargo.h>
 #include <asm/uninorth.h>
 #include <asm/io.h>
@@ -63,6 +67,9 @@
 #define DBG_LOW(x...)
 #endif
 
+
+static int pmac_i2c_force_poll = 1;
+
 /*
  * A bus structure. Each bus in the system has such a structure associated.
  */
@@ -80,6 +87,7 @@ struct pmac_i2c_bus
         struct semaphore        sem;
         int                     opened;
         int                     polled;         /* open mode */
+        struct platform_device  *platform_dev;
 
         /* ops */
         int (*open)(struct pmac_i2c_bus *bus);
@@ -101,6 +109,16 @@ struct pmac_i2c_host_kw
         void __iomem            *base;          /* register base address */
         int                     bsteps;         /* register stepping */
         int                     speed;          /* speed */
+        int                     irq;
+        u8                      *data;
+        unsigned                len;
+        int                     state;
+        int                     rw;
+        int                     polled;
+        int                     result;
+        struct completion       complete;
+        spinlock_t              lock;
+        struct timer_list       timeout_timer;
 };
 
 /* Register indices */
@@ -115,6 +133,8 @@ typedef enum {
         reg_data
 } reg_t;
 
+/* The Tumbler audio equalizer can be really slow sometimes */
+#define KW_POLL_TIMEOUT         (2*HZ)
 
 /* Mode register */
 #define KW_I2C_MODE_100KHZ      0x00
@@ -158,8 +178,9 @@ enum {
 };
 
 #define WRONG_STATE(name) do {\
-                printk(KERN_DEBUG "KW: wrong state. Got %s, state: %s (isr: %02x)\n", \
-                       name, __kw_state_names[state], isr); \
+                printk(KERN_DEBUG "KW: wrong state. Got %s, state: %s " \
+                       "(isr: %02x)\n", \
+                       name, __kw_state_names[host->state], isr); \
         } while(0)
 
 static const char *__kw_state_names[] = {
@@ -171,23 +192,22 @@ static const char *__kw_state_names[] = {
         "state_dead"
 };
 
-static inline u8 __kw_read_reg(struct pmac_i2c_bus *bus, reg_t reg)
+static inline u8 __kw_read_reg(struct pmac_i2c_host_kw *host, reg_t reg)
 {
-        struct pmac_i2c_host_kw *host = bus->hostdata;
         return readb(host->base + (((unsigned int)reg) << host->bsteps));
 }
 
-static inline void __kw_write_reg(struct pmac_i2c_bus *bus, reg_t reg, u8 val)
+static inline void __kw_write_reg(struct pmac_i2c_host_kw *host,
+                                  reg_t reg, u8 val)
 {
-        struct pmac_i2c_host_kw *host = bus->hostdata;
         writeb(val, host->base + (((unsigned)reg) << host->bsteps));
-        (void)__kw_read_reg(bus, reg_subaddr);
+        (void)__kw_read_reg(host, reg_subaddr);
 }
 
-#define kw_write_reg(reg, val)  __kw_write_reg(bus, reg, val)
-#define kw_read_reg(reg)        __kw_read_reg(bus, reg)
+#define kw_write_reg(reg, val)  __kw_write_reg(host, reg, val)
+#define kw_read_reg(reg)        __kw_read_reg(host, reg)
 
-static u8 kw_i2c_wait_interrupt(struct pmac_i2c_bus* bus)
+static u8 kw_i2c_wait_interrupt(struct pmac_i2c_host_kw *host)
 {
         int i, j;
         u8 isr;
@@ -201,8 +221,8 @@ static u8 kw_i2c_wait_interrupt(struct pmac_i2c_bus* bus)
                  * on udelay nor schedule when in polled mode !
                  * For now, just use a bogus loop....
                  */
-                if (bus->polled) {
-                        for (j = 1; j < 1000000; j++)
+                if (host->polled) {
+                        for (j = 1; j < 100000; j++)
                                 mb();
                 } else
                         msleep(1);
@@ -210,86 +230,99 @@ static u8 kw_i2c_wait_interrupt(struct pmac_i2c_bus* bus)
         return isr;
 }
 
-static int kw_i2c_handle_interrupt(struct pmac_i2c_bus *bus, int state, int rw,
-                                   int *rc, u8 **data, int *len, u8 isr)
+static void kw_i2c_handle_interrupt(struct pmac_i2c_host_kw *host, u8 isr)
 {
         u8 ack;
 
         DBG_LOW("kw_handle_interrupt(%s, isr: %x)\n",
-                __kw_state_names[state], isr);
+                __kw_state_names[host->state], isr);
+
+        if (host->state == state_idle) {
+                printk(KERN_WARNING "low_i2c: Keywest got an out of state"
+                       " interrupt, ignoring\n");
+                kw_write_reg(reg_isr, isr);
+                return;
+        }
 
         if (isr == 0) {
-                if (state != state_stop) {
+                if (host->state != state_stop) {
                         DBG_LOW("KW: Timeout !\n");
-                        *rc = -EIO;
+                        host->result = -EIO;
                         goto stop;
                 }
-                if (state == state_stop) {
+                if (host->state == state_stop) {
                         ack = kw_read_reg(reg_status);
-                        if (!(ack & KW_I2C_STAT_BUSY)) {
-                                state = state_idle;
-                                kw_write_reg(reg_ier, 0x00);
-                        }
+                        if (ack & KW_I2C_STAT_BUSY)
+                                kw_write_reg(reg_status, 0);
+                        host->state = state_idle;
+                        kw_write_reg(reg_ier, 0x00);
+                        if (!host->polled)
+                                complete(&host->complete);
                 }
-                return state;
+                return;
         }
 
         if (isr & KW_I2C_IRQ_ADDR) {
                 ack = kw_read_reg(reg_status);
-                if (state != state_addr) {
+                if (host->state != state_addr) {
                         kw_write_reg(reg_isr, KW_I2C_IRQ_ADDR);
                         WRONG_STATE("KW_I2C_IRQ_ADDR"); 
-                        *rc = -EIO;
+                        host->result = -EIO;
                         goto stop;
                 }
                 if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {
-                        *rc = -ENODEV;
+                        host->result = -ENODEV;
                         DBG_LOW("KW: NAK on address\n");
-                        return state_stop;                   
+                        host->state = state_stop;
+                        return;
                 } else {
-                        if (rw) {
-                                state = state_read;
-                                if (*len > 1)
+                        if (host->len == 0) {
+                                kw_write_reg(reg_isr, KW_I2C_IRQ_ADDR);
+                                goto stop;
+                        }
+                        if (host->rw) {
+                                host->state = state_read;
+                                if (host->len > 1)
                                         kw_write_reg(reg_control,
                                                      KW_I2C_CTL_AAK);
                         } else {
-                                state = state_write;
-                                kw_write_reg(reg_data, **data);
-                                (*data)++; (*len)--;
+                                host->state = state_write;
+                                kw_write_reg(reg_data, *(host->data++));
+                                host->len--;
                         }
                 }
                 kw_write_reg(reg_isr, KW_I2C_IRQ_ADDR);
         }
 
         if (isr & KW_I2C_IRQ_DATA) {
-                if (state == state_read) {
-                        **data = kw_read_reg(reg_data);
-                        (*data)++; (*len)--;
+                if (host->state == state_read) {
+                        *(host->data++) = kw_read_reg(reg_data);
+                        host->len--;
                         kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
-                        if ((*len) == 0)
-                                state = state_stop;
-                        else if ((*len) == 1)
+                        if (host->len == 0)
+                                host->state = state_stop;
+                        else if (host->len == 1)
                                 kw_write_reg(reg_control, 0);
-                } else if (state == state_write) {
+                } else if (host->state == state_write) {
                         ack = kw_read_reg(reg_status);
                         if ((ack & KW_I2C_STAT_LAST_AAK) == 0) {
                                 DBG_LOW("KW: nack on data write\n");
-                                *rc = -EIO;
+                                host->result = -EIO;
                                 goto stop;
-                        } else if (*len) {
-                                kw_write_reg(reg_data, **data);
-                                (*data)++; (*len)--;
+                        } else if (host->len) {
+                                kw_write_reg(reg_data, *(host->data++));
+                                host->len--;
                         } else {
                                 kw_write_reg(reg_control, KW_I2C_CTL_STOP);
-                                state = state_stop;
-                                *rc = 0;
+                                host->state = state_stop;
+                                host->result = 0;
                         }
                         kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
                 } else {
                         kw_write_reg(reg_isr, KW_I2C_IRQ_DATA);
                         WRONG_STATE("KW_I2C_IRQ_DATA"); 
-                        if (state != state_stop) {
-                                *rc = -EIO;
+                        if (host->state != state_stop) {
+                                host->result = -EIO;
                                 goto stop;
                         }
                 }
@@ -297,21 +330,54 @@ static int kw_i2c_handle_interrupt(struct pmac_i2c_bus *bus, int state, int rw,
 
         if (isr & KW_I2C_IRQ_STOP) {
                 kw_write_reg(reg_isr, KW_I2C_IRQ_STOP);
-                if (state != state_stop) {
+                if (host->state != state_stop) {
                         WRONG_STATE("KW_I2C_IRQ_STOP");
-                        *rc = -EIO;
+                        host->result = -EIO;
                 }
-                return state_idle;
+                host->state = state_idle;
+                if (!host->polled)
+                        complete(&host->complete);
         }
 
         if (isr & KW_I2C_IRQ_START)
                 kw_write_reg(reg_isr, KW_I2C_IRQ_START);
 
-        return state;
-
+        return;
  stop:
         kw_write_reg(reg_control, KW_I2C_CTL_STOP);     
-        return state_stop;
+        host->state = state_stop;
+        return;
+}
+
+/* Interrupt handler */
+static irqreturn_t kw_i2c_irq(int irq, void *dev_id, struct pt_regs *regs)
+{
+        struct pmac_i2c_host_kw *host = dev_id;
+        unsigned long flags;
+
+        spin_lock_irqsave(&host->lock, flags);
+        del_timer(&host->timeout_timer);
+        kw_i2c_handle_interrupt(host, kw_read_reg(reg_isr));
+        if (host->state != state_idle) {
+                host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT;
+                add_timer(&host->timeout_timer);
+        }
+        spin_unlock_irqrestore(&host->lock, flags);
+        return IRQ_HANDLED;
+}
+
+static void kw_i2c_timeout(unsigned long data)
+{
+        struct pmac_i2c_host_kw *host = (struct pmac_i2c_host_kw *)data;
+        unsigned long flags;
+
+        spin_lock_irqsave(&host->lock, flags);
+        kw_i2c_handle_interrupt(host, kw_read_reg(reg_isr));
+        if (host->state != state_idle) {
+                host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT;
+                add_timer(&host->timeout_timer);
+        }
+        spin_unlock_irqrestore(&host->lock, flags);
 }
 
 static int kw_i2c_open(struct pmac_i2c_bus *bus)
@@ -332,8 +398,7 @@ static int kw_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
 {
         struct pmac_i2c_host_kw *host = bus->hostdata;
         u8 mode_reg = host->speed;
-        int state = state_addr;
-        int rc = 0;
+        int use_irq = host->irq != NO_IRQ && !bus->polled;
 
         /* Setup mode & subaddress if any */
         switch(bus->mode) {
@@ -371,18 +436,50 @@ static int kw_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
             || (mode_reg & KW_I2C_MODE_MODE_MASK) == KW_I2C_MODE_COMBINED)
                 kw_write_reg(reg_subaddr, subaddr);
 
-        /* Start sending address & disable interrupt*/
-        kw_write_reg(reg_ier, 0 /*KW_I2C_IRQ_MASK*/);
+        /* Prepare for async operations */
+        host->data = data;
+        host->len = len;
+        host->state = state_addr;
+        host->result = 0;
+        host->rw = (addrdir & 1);
+        host->polled = bus->polled;
+
+        /* Enable interrupt if not using polled mode and interrupt is
+         * available
+         */
+        if (use_irq) {
+                /* Clear completion */
+                INIT_COMPLETION(host->complete);
+                /* Ack stale interrupts */
+                kw_write_reg(reg_isr, kw_read_reg(reg_isr));
+                /* Arm timeout */
+                host->timeout_timer.expires = jiffies + KW_POLL_TIMEOUT;
+                add_timer(&host->timeout_timer);
+                /* Enable emission */
+                kw_write_reg(reg_ier, KW_I2C_IRQ_MASK);
+        }
+
+        /* Start sending address */
         kw_write_reg(reg_control, KW_I2C_CTL_XADDR);
 
-        /* State machine, to turn into an interrupt handler in the future */
-        while(state != state_idle) {
-                u8 isr = kw_i2c_wait_interrupt(bus);
-                state = kw_i2c_handle_interrupt(bus, state, addrdir & 1, &rc,
-                                                &data, &len, isr);
+        /* Wait for completion */
+        if (use_irq)
+                wait_for_completion(&host->complete);
+        else {
+                while(host->state != state_idle) {
+                        unsigned long flags;
+
+                        u8 isr = kw_i2c_wait_interrupt(host);
+                        spin_lock_irqsave(&host->lock, flags);
+                        kw_i2c_handle_interrupt(host, isr);
+                        spin_unlock_irqrestore(&host->lock, flags);
+                }
         }
 
-        return rc;
+        /* Disable emission */
+        kw_write_reg(reg_ier, 0);
+
+        return host->result;
 }
 
 static struct pmac_i2c_host_kw *__init kw_i2c_host_init(struct device_node *np)
@@ -409,6 +506,12 @@ static struct pmac_i2c_host_kw *__init kw_i2c_host_init(struct device_node *np)
                 return NULL;
         }
         init_MUTEX(&host->mutex);
+        init_completion(&host->complete);
+        spin_lock_init(&host->lock);
+        init_timer(&host->timeout_timer);
+        host->timeout_timer.function = kw_i2c_timeout;
+        host->timeout_timer.data = (unsigned long)host;
+
         psteps = (u32 *)get_property(np, "AAPL,address-step", NULL);
         steps = psteps ? (*psteps) : 0x10;
         for (host->bsteps = 0; (steps & 0x01) == 0; host->bsteps++)
@@ -427,9 +530,28 @@ static struct pmac_i2c_host_kw *__init kw_i2c_host_init(struct device_node *np)
                 host->speed = KW_I2C_MODE_25KHZ;
                 break;
         }       
+        if (np->n_intrs > 0)
+                host->irq = np->intrs[0].line;
+        else
+                host->irq = NO_IRQ;
 
-        printk(KERN_INFO "KeyWest i2c @0x%08x %s\n", *addrp, np->full_name);
         host->base = ioremap((*addrp), 0x1000);
+        if (host->base == NULL) {
+                printk(KERN_ERR "low_i2c: Can't map registers for %s\n",
+                       np->full_name);
+                kfree(host);
+                return NULL;
+        }
+
+        /* Make sure IRA is disabled */
+        kw_write_reg(reg_ier, 0);
+
+        /* Request chip interrupt */
+        if (request_irq(host->irq, kw_i2c_irq, SA_SHIRQ, "keywest i2c", host))
+                host->irq = NO_IRQ;
+
+        printk(KERN_INFO "KeyWest i2c @0x%08x irq %d %s\n",
+               *addrp, host->irq, np->full_name);
 
         return host;
 }
@@ -591,7 +713,7 @@ static int pmu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
                 req->nbytes = sizeof(struct pmu_i2c_hdr) + 1;
                 req->done = pmu_i2c_complete;
                 req->arg = &comp;
-                if (!read) {
+                if (!read && len) {
                         memcpy(hdr->data, data, len);
                         req->nbytes += len;
                 }
@@ -637,7 +759,8 @@ static int pmu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
                                        " bytes, expected %d !\n", rlen, len);
                                 return -EIO;
                         }
-                        memcpy(data, &req->reply[1], len);
+                        if (len)
+                                memcpy(data, &req->reply[1], len);
                         return 0;
                 }
         }
@@ -713,6 +836,10 @@ static int smu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
         int read = addrdir & 1;
         int rc = 0;
 
+        if ((read && len > SMU_I2C_READ_MAX) ||
+            ((!read) && len > SMU_I2C_WRITE_MAX))
+                return -EINVAL;
+
         memset(cmd, 0, sizeof(struct smu_i2c_cmd));
         cmd->info.bus = bus->channel;
         cmd->info.devaddr = addrdir;
@@ -740,7 +867,7 @@ static int smu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
         default:
                 return -EINVAL;
         }
-        if (!read)
+        if (!read && len)
                 memcpy(cmd->info.data, data, len);
 
         init_completion(&comp);
@@ -752,7 +879,7 @@ static int smu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
         wait_for_completion(&comp);
         rc = cmd->status;
 
-        if (read)
+        if (read && len)
                 memcpy(data, cmd->info.data, len);
         return rc < 0 ? rc : 0;
 }
@@ -767,7 +894,7 @@ static void __init smu_i2c_probe(void)
         if (!smu_present())
                 return;
 
-        controller = of_find_node_by_name(NULL, "smu_i2c_control");
+        controller = of_find_node_by_name(NULL, "smu-i2c-control");
         if (controller == NULL)
                 controller = of_find_node_by_name(NULL, "smu");
         if (controller == NULL)
@@ -884,6 +1011,13 @@ int pmac_i2c_get_flags(struct pmac_i2c_bus *bus)
 }
 EXPORT_SYMBOL_GPL(pmac_i2c_get_flags);
 
+int pmac_i2c_get_channel(struct pmac_i2c_bus *bus)
+{
+        return bus->channel;
+}
+EXPORT_SYMBOL_GPL(pmac_i2c_get_channel);
+
+
 void pmac_i2c_attach_adapter(struct pmac_i2c_bus *bus,
                              struct i2c_adapter *adapter)
 {
@@ -906,6 +1040,17 @@ struct i2c_adapter *pmac_i2c_get_adapter(struct pmac_i2c_bus *bus)
 }
 EXPORT_SYMBOL_GPL(pmac_i2c_get_adapter);
 
+struct pmac_i2c_bus *pmac_i2c_adapter_to_bus(struct i2c_adapter *adapter)
+{
+        struct pmac_i2c_bus *bus;
+
+        list_for_each_entry(bus, &pmac_i2c_busses, link)
+                if (bus->adapter == adapter)
+                        return bus;
+        return NULL;
+}
+EXPORT_SYMBOL_GPL(pmac_i2c_adapter_to_bus);
+
 extern int pmac_i2c_match_adapter(struct device_node *dev,
                                   struct i2c_adapter *adapter)
 {
@@ -956,7 +1101,7 @@ int pmac_i2c_open(struct pmac_i2c_bus *bus, int polled)
         int rc;
 
         down(&bus->sem);
-        bus->polled = polled;
+        bus->polled = polled || pmac_i2c_force_poll;
         bus->opened = 1;
         bus->mode = pmac_i2c_mode_std;
         if (bus->open && (rc = bus->open(bus)) != 0) {
@@ -1034,14 +1179,43 @@ int __init pmac_i2c_init(void)
         kw_i2c_probe();
 
 #ifdef CONFIG_ADB_PMU
+        /* Probe PMU i2c busses */
         pmu_i2c_probe();
 #endif
 
 #ifdef CONFIG_PMAC_SMU
+        /* Probe SMU i2c busses */
         smu_i2c_probe();
 #endif
-
         return 0;
 }
 arch_initcall(pmac_i2c_init);
 
+/* Since pmac_i2c_init can be called too early for the platform device
+ * registration, we need to do it at a later time. In our case, subsys
+ * happens to fit well, though I agree it's a bit of a hack...
+ */
+static int __init pmac_i2c_create_platform_devices(void)
+{
+        struct pmac_i2c_bus *bus;
+        int i = 0;
+
+        /* In the case where we are initialized from smp_init(), we must
+         * not use the timer (and thus the irq). It's safe from now on
+         * though
+         */
+        pmac_i2c_force_poll = 0;
+
+        /* Create platform devices */
+        list_for_each_entry(bus, &pmac_i2c_busses, link) {
+                bus->platform_dev =
+                        platform_device_alloc("i2c-powermac", i++);
+                if (bus->platform_dev == NULL)
+                        return -ENOMEM;
+                bus->platform_dev->dev.platform_data = bus;
+                platform_device_add(bus->platform_dev);
+        }
+
+        return 0;
+}
+subsys_initcall(pmac_i2c_create_platform_devices);