i2c: mv64xxx: Add I2C Transaction Generator support

The I2C Transaction Generator offloads CPU from managing I2C
transfer step by step.

This feature is currently only available on Armada XP, so usage of
this mechanism is activated through device tree.

Based on the work of Piotr Ziecik and rewrote to use the new way of
handling multiples i2c messages.

Signed-off-by: Piotr Ziecik <kosmo@semihalf.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Signed-off-by: Wolfram Sang <wsa@the-dreams.de>

1 files changed, 182 insertions, 11 deletions

diff --git a/drivers/i2c/busses/i2c-mv64xxx.c b/drivers/i2c/busses/i2c-mv64xxx.c
index 9cc361d19941..2404c4e0f35c 100644
--- a/drivers/i2c/busses/i2c-mv64xxx.c
+++ b/drivers/i2c/busses/i2c-mv64xxx.c
@@ -55,6 +55,32 @@
 #define MV64XXX_I2C_STATUS_MAST_RD_ADDR_2_NO_ACK        0xe8
 #define MV64XXX_I2C_STATUS_NO_STATUS                    0xf8
 
+/* Register defines (I2C bridge) */
+#define MV64XXX_I2C_REG_TX_DATA_LO                      0xc0
+#define MV64XXX_I2C_REG_TX_DATA_HI                      0xc4
+#define MV64XXX_I2C_REG_RX_DATA_LO                      0xc8
+#define MV64XXX_I2C_REG_RX_DATA_HI                      0xcc
+#define MV64XXX_I2C_REG_BRIDGE_CONTROL                  0xd0
+#define MV64XXX_I2C_REG_BRIDGE_STATUS                   0xd4
+#define MV64XXX_I2C_REG_BRIDGE_INTR_CAUSE               0xd8
+#define MV64XXX_I2C_REG_BRIDGE_INTR_MASK                0xdC
+#define MV64XXX_I2C_REG_BRIDGE_TIMING                   0xe0
+
+/* Bridge Control values */
+#define MV64XXX_I2C_BRIDGE_CONTROL_WR                   0x00000001
+#define MV64XXX_I2C_BRIDGE_CONTROL_RD                   0x00000002
+#define MV64XXX_I2C_BRIDGE_CONTROL_ADDR_SHIFT           2
+#define MV64XXX_I2C_BRIDGE_CONTROL_ADDR_EXT             0x00001000
+#define MV64XXX_I2C_BRIDGE_CONTROL_TX_SIZE_SHIFT        13
+#define MV64XXX_I2C_BRIDGE_CONTROL_RX_SIZE_SHIFT        16
+#define MV64XXX_I2C_BRIDGE_CONTROL_ENABLE               0x00080000
+
+/* Bridge Status values */
+#define MV64XXX_I2C_BRIDGE_STATUS_ERROR                 0x00000001
+#define MV64XXX_I2C_STATUS_OFFLOAD_ERROR                0xf0000001
+#define MV64XXX_I2C_STATUS_OFFLOAD_OK                   0xf0000000
+
+
 /* Driver states */
 enum {
         MV64XXX_I2C_STATE_INVALID,
@@ -71,14 +97,17 @@ enum {
 enum {
         MV64XXX_I2C_ACTION_INVALID,
         MV64XXX_I2C_ACTION_CONTINUE,
+        MV64XXX_I2C_ACTION_OFFLOAD_SEND_START,
         MV64XXX_I2C_ACTION_SEND_START,
         MV64XXX_I2C_ACTION_SEND_RESTART,
+        MV64XXX_I2C_ACTION_OFFLOAD_RESTART,
         MV64XXX_I2C_ACTION_SEND_ADDR_1,
         MV64XXX_I2C_ACTION_SEND_ADDR_2,
         MV64XXX_I2C_ACTION_SEND_DATA,
         MV64XXX_I2C_ACTION_RCV_DATA,
         MV64XXX_I2C_ACTION_RCV_DATA_STOP,
         MV64XXX_I2C_ACTION_SEND_STOP,
+        MV64XXX_I2C_ACTION_OFFLOAD_SEND_STOP,
 };
 
 struct mv64xxx_i2c_regs {
@@ -117,6 +146,7 @@ struct mv64xxx_i2c_data {
         spinlock_t              lock;
         struct i2c_msg          *msg;
         struct i2c_adapter      adapter;
+        bool                    offload_enabled;
 };
 
 static struct mv64xxx_i2c_regs mv64xxx_i2c_regs_mv64xxx = {
@@ -165,6 +195,77 @@ mv64xxx_i2c_prepare_for_io(struct mv64xxx_i2c_data *drv_data,
         }
 }
 
+static int mv64xxx_i2c_offload_msg(struct mv64xxx_i2c_data *drv_data)
+{
+        unsigned long data_reg_hi = 0;
+        unsigned long data_reg_lo = 0;
+        unsigned long ctrl_reg;
+        struct i2c_msg *msg = drv_data->msgs;
+
+        drv_data->msg = msg;
+        drv_data->byte_posn = 0;
+        drv_data->bytes_left = msg->len;
+        drv_data->aborting = 0;
+        drv_data->rc = 0;
+        /* Only regular transactions can be offloaded */
+        if ((msg->flags & ~(I2C_M_TEN | I2C_M_RD)) != 0)
+                return -EINVAL;
+
+        /* Only 1-8 byte transfers can be offloaded */
+        if (msg->len < 1 || msg->len > 8)
+                return -EINVAL;
+
+        /* Build transaction */
+        ctrl_reg = MV64XXX_I2C_BRIDGE_CONTROL_ENABLE |
+                   (msg->addr << MV64XXX_I2C_BRIDGE_CONTROL_ADDR_SHIFT);
+
+        if ((msg->flags & I2C_M_TEN) != 0)
+                ctrl_reg |=  MV64XXX_I2C_BRIDGE_CONTROL_ADDR_EXT;
+
+        if ((msg->flags & I2C_M_RD) == 0) {
+                u8 local_buf[8] = { 0 };
+
+                memcpy(local_buf, msg->buf, msg->len);
+                data_reg_lo = cpu_to_le32(*((u32 *)local_buf));
+                data_reg_hi = cpu_to_le32(*((u32 *)(local_buf+4)));
+
+                ctrl_reg |= MV64XXX_I2C_BRIDGE_CONTROL_WR |
+                    (msg->len - 1) << MV64XXX_I2C_BRIDGE_CONTROL_TX_SIZE_SHIFT;
+
+                writel_relaxed(data_reg_lo,
+                        drv_data->reg_base + MV64XXX_I2C_REG_TX_DATA_LO);
+                writel_relaxed(data_reg_hi,
+                        drv_data->reg_base + MV64XXX_I2C_REG_TX_DATA_HI);
+
+        } else {
+                ctrl_reg |= MV64XXX_I2C_BRIDGE_CONTROL_RD |
+                    (msg->len - 1) << MV64XXX_I2C_BRIDGE_CONTROL_RX_SIZE_SHIFT;
+        }
+
+        /* Execute transaction */
+        writel(ctrl_reg, drv_data->reg_base + MV64XXX_I2C_REG_BRIDGE_CONTROL);
+
+        return 0;
+}
+
+static void
+mv64xxx_i2c_update_offload_data(struct mv64xxx_i2c_data *drv_data)
+{
+        struct i2c_msg *msg = drv_data->msg;
+
+        if (msg->flags & I2C_M_RD) {
+                u32 data_reg_lo = readl(drv_data->reg_base +
+                                MV64XXX_I2C_REG_RX_DATA_LO);
+                u32 data_reg_hi = readl(drv_data->reg_base +
+                                MV64XXX_I2C_REG_RX_DATA_HI);
+                u8 local_buf[8] = { 0 };
+
+                *((u32 *)local_buf) = le32_to_cpu(data_reg_lo);
+                *((u32 *)(local_buf+4)) = le32_to_cpu(data_reg_hi);
+                memcpy(msg->buf, local_buf, msg->len);
+        }
+
+}
 /*
  *****************************************************************************
  *
@@ -177,6 +278,15 @@ mv64xxx_i2c_prepare_for_io(struct mv64xxx_i2c_data *drv_data,
 static void
 mv64xxx_i2c_hw_init(struct mv64xxx_i2c_data *drv_data)
 {
+        if (drv_data->offload_enabled) {
+                writel(0, drv_data->reg_base + MV64XXX_I2C_REG_BRIDGE_CONTROL);
+                writel(0, drv_data->reg_base + MV64XXX_I2C_REG_BRIDGE_TIMING);
+                writel(0, drv_data->reg_base +
+                        MV64XXX_I2C_REG_BRIDGE_INTR_CAUSE);
+                writel(0, drv_data->reg_base +
+                        MV64XXX_I2C_REG_BRIDGE_INTR_MASK);
+        }
+
         writel(0, drv_data->reg_base + drv_data->reg_offsets.soft_reset);
         writel(MV64XXX_I2C_BAUD_DIV_M(drv_data->freq_m) | MV64XXX_I2C_BAUD_DIV_N(drv_data->freq_n),
                 drv_data->reg_base + drv_data->reg_offsets.clock);
@@ -283,6 +393,16 @@ mv64xxx_i2c_fsm(struct mv64xxx_i2c_data *drv_data, u32 status)
                 drv_data->rc = -ENXIO;
                 break;
 
+        case MV64XXX_I2C_STATUS_OFFLOAD_OK:
+                if (drv_data->send_stop || drv_data->aborting) {
+                        drv_data->action = MV64XXX_I2C_ACTION_OFFLOAD_SEND_STOP;
+                        drv_data->state = MV64XXX_I2C_STATE_IDLE;
+                } else {
+                        drv_data->action = MV64XXX_I2C_ACTION_OFFLOAD_RESTART;
+                        drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_RESTART;
+                }
+                break;
+
         default:
                 dev_err(&drv_data->adapter.dev,
                         "mv64xxx_i2c_fsm: Ctlr Error -- state: 0x%x, "
@@ -299,20 +419,27 @@ static void
 mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
 {
         switch(drv_data->action) {
+        case MV64XXX_I2C_ACTION_OFFLOAD_RESTART:
+                mv64xxx_i2c_update_offload_data(drv_data);
+                writel(0, drv_data->reg_base +  MV64XXX_I2C_REG_BRIDGE_CONTROL);
+                writel(0, drv_data->reg_base +
+                        MV64XXX_I2C_REG_BRIDGE_INTR_CAUSE);
+                /* FALLTHRU */
         case MV64XXX_I2C_ACTION_SEND_RESTART:
                 /* We should only get here if we have further messages */
                 BUG_ON(drv_data->num_msgs == 0);
 
-                drv_data->cntl_bits |= MV64XXX_I2C_REG_CONTROL_START;
-                writel(drv_data->cntl_bits,
-                        drv_data->reg_base + drv_data->reg_offsets.control);
-
                 drv_data->msgs++;
                 drv_data->num_msgs--;
+                if (!(drv_data->offload_enabled &&
+                                mv64xxx_i2c_offload_msg(drv_data))) {
+                        drv_data->cntl_bits |= MV64XXX_I2C_REG_CONTROL_START;
+                        writel(drv_data->cntl_bits,
+                        drv_data->reg_base + drv_data->reg_offsets.control);
 
-                /* Setup for the next message */
-                mv64xxx_i2c_prepare_for_io(drv_data, drv_data->msgs);
-
+                        /* Setup for the next message */
+                        mv64xxx_i2c_prepare_for_io(drv_data, drv_data->msgs);
+                }
                 /*
                  * We're never at the start of the message here, and by this
                  * time it's already too late to do any protocol mangling.
@@ -326,6 +453,12 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
                         drv_data->reg_base + drv_data->reg_offsets.control);
                 break;
 
+        case MV64XXX_I2C_ACTION_OFFLOAD_SEND_START:
+                if (!mv64xxx_i2c_offload_msg(drv_data))
+                        break;
+                else
+                        drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
+                /* FALLTHRU */
         case MV64XXX_I2C_ACTION_SEND_START:
                 writel(drv_data->cntl_bits | MV64XXX_I2C_REG_CONTROL_START,
                         drv_data->reg_base + drv_data->reg_offsets.control);
@@ -375,6 +508,7 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
                         "mv64xxx_i2c_do_action: Invalid action: %d\n",
                         drv_data->action);
                 drv_data->rc = -EIO;
+
                 /* FALLTHRU */
         case MV64XXX_I2C_ACTION_SEND_STOP:
                 drv_data->cntl_bits &= ~MV64XXX_I2C_REG_CONTROL_INTEN;
@@ -383,6 +517,15 @@ mv64xxx_i2c_do_action(struct mv64xxx_i2c_data *drv_data)
                 drv_data->block = 0;
                 wake_up(&drv_data->waitq);
                 break;
+
+        case MV64XXX_I2C_ACTION_OFFLOAD_SEND_STOP:
+                mv64xxx_i2c_update_offload_data(drv_data);
+                writel(0, drv_data->reg_base +  MV64XXX_I2C_REG_BRIDGE_CONTROL);
+                writel(0, drv_data->reg_base +
+                        MV64XXX_I2C_REG_BRIDGE_INTR_CAUSE);
+                drv_data->block = 0;
+                wake_up(&drv_data->waitq);
+                break;
         }
 }
 
@@ -395,6 +538,21 @@ mv64xxx_i2c_intr(int irq, void *dev_id)
         irqreturn_t     rc = IRQ_NONE;
 
         spin_lock_irqsave(&drv_data->lock, flags);
+
+        if (drv_data->offload_enabled) {
+                while (readl(drv_data->reg_base +
+                                MV64XXX_I2C_REG_BRIDGE_INTR_CAUSE)) {
+                        int reg_status = readl(drv_data->reg_base +
+                                        MV64XXX_I2C_REG_BRIDGE_STATUS);
+                        if (reg_status & MV64XXX_I2C_BRIDGE_STATUS_ERROR)
+                                status = MV64XXX_I2C_STATUS_OFFLOAD_ERROR;
+                        else
+                                status = MV64XXX_I2C_STATUS_OFFLOAD_OK;
+                        mv64xxx_i2c_fsm(drv_data, status);
+                        mv64xxx_i2c_do_action(drv_data);
+                        rc = IRQ_HANDLED;
+                }
+        }
         while (readl(drv_data->reg_base + drv_data->reg_offsets.control) &
                                                 MV64XXX_I2C_REG_CONTROL_IFLG) {
                 status = readl(drv_data->reg_base + drv_data->reg_offsets.status);
@@ -459,11 +617,15 @@ mv64xxx_i2c_execute_msg(struct mv64xxx_i2c_data *drv_data, struct i2c_msg *msg,
         unsigned long   flags;
 
         spin_lock_irqsave(&drv_data->lock, flags);
-        mv64xxx_i2c_prepare_for_io(drv_data, msg);
-
-        drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
-        drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
+        if (drv_data->offload_enabled) {
+                drv_data->action = MV64XXX_I2C_ACTION_OFFLOAD_SEND_START;
+                drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
+        } else {
+                mv64xxx_i2c_prepare_for_io(drv_data, msg);
 
+                drv_data->action = MV64XXX_I2C_ACTION_SEND_START;
+                drv_data->state = MV64XXX_I2C_STATE_WAITING_FOR_START_COND;
+        }
         drv_data->send_stop = is_last;
         drv_data->block = 1;
         mv64xxx_i2c_do_action(drv_data);
@@ -521,6 +683,7 @@ static const struct i2c_algorithm mv64xxx_i2c_algo = {
 static const struct of_device_id mv64xxx_i2c_of_match_table[] = {
         { .compatible = "allwinner,sun4i-i2c", .data = &mv64xxx_i2c_regs_sun4i},
         { .compatible = "marvell,mv64xxx-i2c", .data = &mv64xxx_i2c_regs_mv64xxx},
+        { .compatible = "marvell,mv78230-i2c", .data = &mv64xxx_i2c_regs_mv64xxx},
         {}
 };
 MODULE_DEVICE_TABLE(of, mv64xxx_i2c_of_match_table);
@@ -601,6 +764,13 @@ mv64xxx_of_config(struct mv64xxx_i2c_data *drv_data,
 
         memcpy(&drv_data->reg_offsets, device->data, sizeof(drv_data->reg_offsets));
 
+        /*
+         * For controllers embedded in new SoCs activate the
+         * Transaction Generator support.
+         */
+        if (of_device_is_compatible(np, "marvell,mv78230-i2c"))
+                drv_data->offload_enabled = true;
+
 out:
         return rc;
 #endif
@@ -654,6 +824,7 @@ mv64xxx_i2c_probe(struct platform_device *pd)
                 drv_data->freq_n = pdata->freq_n;
                 drv_data->irq = platform_get_irq(pd, 0);
                 drv_data->adapter.timeout = msecs_to_jiffies(pdata->timeout);
+                drv_data->offload_enabled = false;
                 memcpy(&drv_data->reg_offsets, &mv64xxx_i2c_regs_mv64xxx, sizeof(drv_data->reg_offsets));
         } else if (pd->dev.of_node) {
                 rc = mv64xxx_of_config(drv_data, &pd->dev);