mfd: iqs62x: Do not poll during ATI

After loading firmware, the driver triggers ATI (calibration) with
the newly loaded register configuration in place. Next, the driver
polls a register field to ensure ATI completed in a timely fashion
and that the device is ready to sense.

However, communicating with the device over I2C while ATI is under-
way may induce noise in the device and cause ATI to fail. As such,
the vendor recommends not to poll the device during ATI.

To solve this problem, let the device naturally signal to the host
that ATI is complete by way of an interrupt. A completion prevents
the sub-devices from being registered until this happens.

The former logic that scaled ATI timeout and filter settling delay
is not carried forward with the new implementation, as it produces
overly conservative delays at lower clock rates. Instead, a single
pair of delays that covers all cases is used.

Signed-off-by: Jeff LaBundy <jeff@labundy.com>
Signed-off-by: Lee Jones <lee.jones@linaro.org>

diff --git a/drivers/mfd/iqs62x.c b/drivers/mfd/iqs62x.c
index 07c97253171566e94d28054b207383868eb82333..9b5c389ca2c313f319d93bd34a2d2fe8416e9bc2 100644 (file)
--- a/drivers/mfd/iqs62x.c
+++ b/drivers/mfd/iqs62x.c
@@ -36,7 +36,6 @@
 #define IQS62X_PROD_NUM                                0x00
 
 #define IQS62X_SYS_FLAGS                       0x10
-#define IQS62X_SYS_FLAGS_IN_ATI                        BIT(2)
 
 #define IQS620_HALL_FLAGS                      0x16
 #define IQS621_HALL_FLAGS                      0x19
@@ -60,6 +59,7 @@
 #define IQS62X_SYS_SETTINGS_ACK_RESET          BIT(6)
 #define IQS62X_SYS_SETTINGS_EVENT_MODE         BIT(5)
 #define IQS62X_SYS_SETTINGS_CLK_DIV            BIT(4)
+#define IQS62X_SYS_SETTINGS_COMM_ATI           BIT(3)
 #define IQS62X_SYS_SETTINGS_REDO_ATI           BIT(1)
 
 #define IQS62X_PWR_SETTINGS                    0xD2
@@ -81,9 +81,7 @@
 #define IQS62X_FW_REC_TYPE_MASK                        3
 #define IQS62X_FW_REC_TYPE_DATA                        4
 
-#define IQS62X_ATI_POLL_SLEEP_US               10000
-#define IQS62X_ATI_POLL_TIMEOUT_US             500000
-#define IQS62X_ATI_STABLE_DELAY_MS             150
+#define IQS62X_FILT_SETTLE_MS                  250
 
 struct iqs62x_fw_rec {
        u8 type;
@@ -111,7 +109,6 @@ static int iqs62x_dev_init(struct iqs62x_core *iqs62x)
        struct iqs62x_fw_blk *fw_blk;
        unsigned int val;
        int ret;
-       u8 clk_div = 1;
 
        list_for_each_entry(fw_blk, &iqs62x->fw_blk_head, list) {
                if (fw_blk->mask)
@@ -181,28 +178,32 @@ static int iqs62x_dev_init(struct iqs62x_core *iqs62x)
                        return ret;
        }
 
-       ret = regmap_read(iqs62x->regmap, IQS62X_SYS_SETTINGS, &val);
-       if (ret)
-               return ret;
-
-       if (val & IQS62X_SYS_SETTINGS_CLK_DIV)
-               clk_div = iqs62x->dev_desc->clk_div;
-
-       ret = regmap_write(iqs62x->regmap, IQS62X_SYS_SETTINGS, val |
-                          IQS62X_SYS_SETTINGS_ACK_RESET |
-                          IQS62X_SYS_SETTINGS_EVENT_MODE |
-                          IQS62X_SYS_SETTINGS_REDO_ATI);
-       if (ret)
-               return ret;
-
-       ret = regmap_read_poll_timeout(iqs62x->regmap, IQS62X_SYS_FLAGS, val,
-                                      !(val & IQS62X_SYS_FLAGS_IN_ATI),
-                                      IQS62X_ATI_POLL_SLEEP_US,
-                                      IQS62X_ATI_POLL_TIMEOUT_US * clk_div);
+       /*
+        * Place the device in streaming mode at first so as not to miss the
+        * limited number of interrupts that would otherwise occur after ATI
+        * completes. The device is subsequently placed in event mode by the
+        * interrupt handler.
+        *
+        * In the meantime, mask interrupts during ATI to prevent the device
+        * from soliciting I2C traffic until the noise-sensitive ATI process
+        * is complete.
+        */
+       ret = regmap_update_bits(iqs62x->regmap, IQS62X_SYS_SETTINGS,
+                                IQS62X_SYS_SETTINGS_ACK_RESET |
+                                IQS62X_SYS_SETTINGS_EVENT_MODE |
+                                IQS62X_SYS_SETTINGS_COMM_ATI |
+                                IQS62X_SYS_SETTINGS_REDO_ATI,
+                                IQS62X_SYS_SETTINGS_ACK_RESET |
+                                IQS62X_SYS_SETTINGS_REDO_ATI);
        if (ret)
                return ret;
 
-       msleep(IQS62X_ATI_STABLE_DELAY_MS * clk_div);
+       /*
+        * The following delay gives the device time to deassert its RDY output
+        * in case a communication window was open while the REDO_ATI field was
+        * written. This prevents an interrupt from being serviced prematurely.
+        */
+       usleep_range(5000, 5100);
 
        return 0;
 }
@@ -433,6 +434,11 @@ const struct iqs62x_event_desc iqs62x_events[IQS62X_NUM_EVENTS] = {
                .mask   = BIT(7),
                .val    = BIT(7),
        },
+       [IQS62X_EVENT_SYS_ATI] = {
+               .reg    = IQS62X_EVENT_SYS,
+               .mask   = BIT(2),
+               .val    = BIT(2),
+       },
 };
 EXPORT_SYMBOL_GPL(iqs62x_events);
 
@@ -521,12 +527,39 @@ static irqreturn_t iqs62x_irq(int irq, void *context)
                                "Failed to re-initialize device: %d\n", ret);
                        return IRQ_NONE;
                }
+
+               iqs62x->event_cache |= BIT(IQS62X_EVENT_SYS_RESET);
+               reinit_completion(&iqs62x->ati_done);
+       } else if (event_flags & BIT(IQS62X_EVENT_SYS_ATI)) {
+               iqs62x->event_cache |= BIT(IQS62X_EVENT_SYS_ATI);
+               reinit_completion(&iqs62x->ati_done);
+       } else if (!completion_done(&iqs62x->ati_done)) {
+               ret = regmap_update_bits(iqs62x->regmap, IQS62X_SYS_SETTINGS,
+                                        IQS62X_SYS_SETTINGS_EVENT_MODE, 0xFF);
+               if (ret) {
+                       dev_err(&client->dev,
+                               "Failed to enable event mode: %d\n", ret);
+                       return IRQ_NONE;
+               }
+
+               msleep(IQS62X_FILT_SETTLE_MS);
+               complete_all(&iqs62x->ati_done);
        }
 
-       ret = blocking_notifier_call_chain(&iqs62x->nh, event_flags,
-                                          &event_data);
-       if (ret & NOTIFY_STOP_MASK)
-               return IRQ_NONE;
+       /*
+        * Reset and ATI events are not broadcast to the sub-device drivers
+        * until ATI has completed. Any other events that may have occurred
+        * during ATI are ignored.
+        */
+       if (completion_done(&iqs62x->ati_done)) {
+               event_flags |= iqs62x->event_cache;
+               ret = blocking_notifier_call_chain(&iqs62x->nh, event_flags,
+                                                  &event_data);
+               if (ret & NOTIFY_STOP_MASK)
+                       return IRQ_NONE;
+
+               iqs62x->event_cache = 0;
+       }
 
        /*
         * Once the communication window is closed, a small delay is added to
@@ -567,6 +600,12 @@ static void iqs62x_firmware_load(const struct firmware *fw, void *context)
                goto err_out;
        }
 
+       if (!wait_for_completion_timeout(&iqs62x->ati_done,
+                                        msecs_to_jiffies(2000))) {
+               dev_err(&client->dev, "Failed to complete ATI\n");
+               goto err_out;
+       }
+
        ret = devm_mfd_add_devices(&client->dev, PLATFORM_DEVID_NONE,
                                   iqs62x->dev_desc->sub_devs,
                                   iqs62x->dev_desc->num_sub_devs,
@@ -748,22 +787,17 @@ static const struct iqs62x_dev_desc iqs62x_devs[] = {
                .dev_name       = "iqs620at",
                .sub_devs       = iqs620at_sub_devs,
                .num_sub_devs   = ARRAY_SIZE(iqs620at_sub_devs),
-
                .prod_num       = IQS620_PROD_NUM,
                .sw_num         = 0x08,
                .cal_regs       = iqs620at_cal_regs,
                .num_cal_regs   = ARRAY_SIZE(iqs620at_cal_regs),
-
                .prox_mask      = BIT(0),
                .sar_mask       = BIT(1) | BIT(7),
                .hall_mask      = BIT(2),
                .hyst_mask      = BIT(3),
                .temp_mask      = BIT(4),
-
                .prox_settings  = IQS620_PROX_SETTINGS_4,
                .hall_flags     = IQS620_HALL_FLAGS,
-
-               .clk_div        = 4,
                .fw_name        = "iqs620a.bin",
                .event_regs     = &iqs620a_event_regs[IQS62X_UI_PROX],
        },
@@ -771,20 +805,15 @@ static const struct iqs62x_dev_desc iqs62x_devs[] = {
                .dev_name       = "iqs620a",
                .sub_devs       = iqs620a_sub_devs,
                .num_sub_devs   = ARRAY_SIZE(iqs620a_sub_devs),
-
                .prod_num       = IQS620_PROD_NUM,
                .sw_num         = 0x08,
-
                .prox_mask      = BIT(0),
                .sar_mask       = BIT(1) | BIT(7),
                .hall_mask      = BIT(2),
                .hyst_mask      = BIT(3),
                .temp_mask      = BIT(4),
-
                .prox_settings  = IQS620_PROX_SETTINGS_4,
                .hall_flags     = IQS620_HALL_FLAGS,
-
-               .clk_div        = 4,
                .fw_name        = "iqs620a.bin",
                .event_regs     = &iqs620a_event_regs[IQS62X_UI_PROX],
        },
@@ -792,23 +821,18 @@ static const struct iqs62x_dev_desc iqs62x_devs[] = {
                .dev_name       = "iqs621",
                .sub_devs       = iqs621_sub_devs,
                .num_sub_devs   = ARRAY_SIZE(iqs621_sub_devs),
-
                .prod_num       = IQS621_PROD_NUM,
                .sw_num         = 0x09,
                .cal_regs       = iqs621_cal_regs,
                .num_cal_regs   = ARRAY_SIZE(iqs621_cal_regs),
-
                .prox_mask      = BIT(0),
                .hall_mask      = BIT(1),
                .als_mask       = BIT(2),
                .hyst_mask      = BIT(3),
                .temp_mask      = BIT(4),
-
                .als_flags      = IQS621_ALS_FLAGS,
                .hall_flags     = IQS621_HALL_FLAGS,
                .hyst_shift     = 5,
-
-               .clk_div        = 2,
                .fw_name        = "iqs621.bin",
                .event_regs     = &iqs621_event_regs[IQS62X_UI_PROX],
        },
@@ -816,21 +840,16 @@ static const struct iqs62x_dev_desc iqs62x_devs[] = {
                .dev_name       = "iqs622",
                .sub_devs       = iqs622_sub_devs,
                .num_sub_devs   = ARRAY_SIZE(iqs622_sub_devs),
-
                .prod_num       = IQS622_PROD_NUM,
                .sw_num         = 0x06,
-
                .prox_mask      = BIT(0),
                .sar_mask       = BIT(1),
                .hall_mask      = BIT(2),
                .als_mask       = BIT(3),
                .ir_mask        = BIT(4),
-
                .prox_settings  = IQS622_PROX_SETTINGS_4,
                .als_flags      = IQS622_ALS_FLAGS,
                .hall_flags     = IQS622_HALL_FLAGS,
-
-               .clk_div        = 2,
                .fw_name        = "iqs622.bin",
                .event_regs     = &iqs622_event_regs[IQS62X_UI_PROX],
        },
@@ -838,14 +857,10 @@ static const struct iqs62x_dev_desc iqs62x_devs[] = {
                .dev_name       = "iqs624",
                .sub_devs       = iqs624_sub_devs,
                .num_sub_devs   = ARRAY_SIZE(iqs624_sub_devs),
-
                .prod_num       = IQS624_PROD_NUM,
                .sw_num         = 0x0B,
-
                .interval       = IQS624_INTERVAL_NUM,
                .interval_div   = 3,
-
-               .clk_div        = 2,
                .fw_name        = "iqs624.bin",
                .event_regs     = &iqs624_event_regs[IQS62X_UI_PROX],
        },
@@ -853,14 +868,10 @@ static const struct iqs62x_dev_desc iqs62x_devs[] = {
                .dev_name       = "iqs625",
                .sub_devs       = iqs625_sub_devs,
                .num_sub_devs   = ARRAY_SIZE(iqs625_sub_devs),
-
                .prod_num       = IQS625_PROD_NUM,
                .sw_num         = 0x0B,
-
                .interval       = IQS625_INTERVAL_NUM,
                .interval_div   = 10,
-
-               .clk_div        = 2,
                .fw_name        = "iqs625.bin",
                .event_regs     = &iqs625_event_regs[IQS62X_UI_PROX],
        },
@@ -890,6 +901,8 @@ static int iqs62x_probe(struct i2c_client *client)
 
        BLOCKING_INIT_NOTIFIER_HEAD(&iqs62x->nh);
        INIT_LIST_HEAD(&iqs62x->fw_blk_head);
+
+       init_completion(&iqs62x->ati_done);
        init_completion(&iqs62x->fw_done);
 
        iqs62x->regmap = devm_regmap_init_i2c(client, &iqs62x_regmap_config);

diff --git a/include/linux/mfd/iqs62x.h b/include/linux/mfd/iqs62x.h
index 043d3b6de9ecbfe8e8cb0fcec09075fedab37d01..5ced55eae11b6b38ca0e44bfdb048178ed364b92 100644 (file)
--- a/include/linux/mfd/iqs62x.h
+++ b/include/linux/mfd/iqs62x.h
@@ -28,7 +28,7 @@
 #define IQS620_GLBL_EVENT_MASK_PMU             BIT(6)
 
 #define IQS62X_NUM_KEYS                                16
-#define IQS62X_NUM_EVENTS                      (IQS62X_NUM_KEYS + 5)
+#define IQS62X_NUM_EVENTS                      (IQS62X_NUM_KEYS + 6)
 
 #define IQS62X_EVENT_SIZE                      10
 
@@ -78,6 +78,7 @@ enum iqs62x_event_flag {
 
        /* everything else */
        IQS62X_EVENT_SYS_RESET,
+       IQS62X_EVENT_SYS_ATI,
 };
 
 struct iqs62x_event_data {
@@ -97,12 +98,10 @@ struct iqs62x_dev_desc {
        const char *dev_name;
        const struct mfd_cell *sub_devs;
        int num_sub_devs;
-
        u8 prod_num;
        u8 sw_num;
        const u8 *cal_regs;
        int num_cal_regs;
-
        u8 prox_mask;
        u8 sar_mask;
        u8 hall_mask;
@@ -110,16 +109,12 @@ struct iqs62x_dev_desc {
        u8 temp_mask;
        u8 als_mask;
        u8 ir_mask;
-
        u8 prox_settings;
        u8 als_flags;
        u8 hall_flags;
        u8 hyst_shift;
-
        u8 interval;
        u8 interval_div;
-
-       u8 clk_div;
        const char *fw_name;
        const enum iqs62x_event_reg (*event_regs)[IQS62X_EVENT_SIZE];
 };
@@ -130,8 +125,10 @@ struct iqs62x_core {
        struct regmap *regmap;
        struct blocking_notifier_head nh;
        struct list_head fw_blk_head;
+       struct completion ati_done;
        struct completion fw_done;
        enum iqs62x_ui_sel ui_sel;
+       unsigned long event_cache;
 };
 
 extern const struct iqs62x_event_desc iqs62x_events[IQS62X_NUM_EVENTS];