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From 2977dc08b02dd7097791a4d3c94796f33a165abc Mon Sep 17 00:00:00 2001
From: Dave Stevenson <dave.stevenson@raspberrypi.com>
Date: Tue, 3 Jan 2023 15:38:08 +0000
Subject: [PATCH] media: dw9807-vcm: Add support for DW9817
 bidirectional VCM driver

The DW9817 is effectively the same as DW9807 from a programming
interface, however it drives +/-100mA instead of 0-100mA. This means
that the power on ramp needs to take the lens from the midpoint, and
power off return it there. It also changes the default position for
the module.

Signed-off-by: Dave Stevenson <dave.stevenson@raspberrypi.com>
---
 drivers/media/i2c/dw9807-vcm.c | 115 +++++++++++++++++++++++++--------
 1 file changed, 88 insertions(+), 27 deletions(-)

--- a/drivers/media/i2c/dw9807-vcm.c
+++ b/drivers/media/i2c/dw9807-vcm.c
@@ -1,6 +1,14 @@
 // SPDX-License-Identifier: GPL-2.0
 // Copyright (C) 2018 Intel Corporation
 
+/*
+ * DW9807 is a 10-bit DAC driver, capable of sinking up to 100mA.
+ *
+ * DW9817 is a bidirectional 10-bit driver, driving up to +/- 100mA.
+ * Operationally it is identical to DW9807, except that the idle position is
+ * the mid-point, not 0.
+ */
+
 #include <linux/acpi.h>
 #include <linux/delay.h>
 #include <linux/i2c.h>
@@ -38,10 +46,16 @@
 
 #define MAX_RETRY              10
 
+struct dw9807_cfg {
+       unsigned int idle_pos;
+       unsigned int default_pos;
+};
+
 struct dw9807_device {
        struct v4l2_ctrl_handler ctrls_vcm;
        struct v4l2_subdev sd;
        u16 current_val;
+       u16 idle_pos;
 };
 
 static inline struct dw9807_device *sd_to_dw9807_vcm(
@@ -109,6 +123,40 @@ static int dw9807_set_dac(struct i2c_cli
        return 0;
 }
 
+/*
+ * The lens position is gradually moved in units of DW9807_CTRL_STEPS,
+ * to make the movements smoothly. In all cases, even when "start" and
+ * "end" are the same, the lens will be set to the "end" position.
+ *
+ * (We don't use hardware slew rate control, because it differs widely
+ * between otherwise-compatible ICs, and may need lens-specific tuning.)
+ */
+static int dw9807_ramp(struct i2c_client *client, int start, int end)
+{
+       int step, val, ret;
+
+       if (start < end)
+               step = DW9807_CTRL_STEPS;
+       else
+               step = -DW9807_CTRL_STEPS;
+
+       val = start;
+       while (true) {
+               val += step;
+               if (step * (val - end) >= 0)
+                       val = end;
+               ret = dw9807_set_dac(client, val);
+               if (ret)
+                       dev_err_ratelimited(&client->dev, "%s I2C failure: %d",
+                                           __func__, ret);
+               if (val == end)
+                       break;
+               usleep_range(DW9807_CTRL_DELAY_US, DW9807_CTRL_DELAY_US + 10);
+       }
+
+       return ret;
+}
+
 static int dw9807_set_ctrl(struct v4l2_ctrl *ctrl)
 {
        struct dw9807_device *dev_vcm = container_of(ctrl->handler,
@@ -118,7 +166,7 @@ static int dw9807_set_ctrl(struct v4l2_c
                struct i2c_client *client = v4l2_get_subdevdata(&dev_vcm->sd);
 
                dev_vcm->current_val = ctrl->val;
-               return dw9807_set_dac(client, ctrl->val);
+               return dw9807_ramp(client, ctrl->val, ctrl->val);
        }
 
        return -EINVAL;
@@ -163,7 +211,8 @@ static int dw9807_init_controls(struct d
        v4l2_ctrl_handler_init(hdl, 1);
 
        v4l2_ctrl_new_std(hdl, ops, V4L2_CID_FOCUS_ABSOLUTE,
-                         0, DW9807_MAX_FOCUS_POS, DW9807_FOCUS_STEPS, 0);
+                         0, DW9807_MAX_FOCUS_POS, DW9807_FOCUS_STEPS,
+                         dev_vcm->current_val);
 
        dev_vcm->sd.ctrl_handler = hdl;
        if (hdl->error) {
@@ -175,9 +224,32 @@ static int dw9807_init_controls(struct d
        return 0;
 }
 
+/* Compatible devices; in fact there are many similar chips.
+ * "data" holds the powered-off (zero current) lens position and a
+ * default/initial control value (which need not be the same as the powered-off
+ * value).
+ */
+static const struct dw9807_cfg dw9807_cfg = {
+       .idle_pos = 0,
+       .default_pos = 0
+};
+
+static const struct dw9807_cfg dw9817_cfg = {
+       .idle_pos = 512,
+       .default_pos = 480,
+};
+
+static const struct of_device_id dw9807_of_table[] = {
+       { .compatible = "dongwoon,dw9807-vcm", .data = &dw9807_cfg },
+       { .compatible = "dongwoon,dw9817-vcm", .data = &dw9817_cfg },
+       { /* sentinel */ }
+};
+
 static int dw9807_probe(struct i2c_client *client)
 {
        struct dw9807_device *dw9807_dev;
+       const struct of_device_id *match;
+       const struct dw9807_cfg *cfg;
        int rval;
 
        dw9807_dev = devm_kzalloc(&client->dev, sizeof(*dw9807_dev),
@@ -185,6 +257,13 @@ static int dw9807_probe(struct i2c_clien
        if (dw9807_dev == NULL)
                return -ENOMEM;
 
+       match = i2c_of_match_device(dw9807_of_table, client);
+       if (match) {
+               cfg = (const struct dw9807_cfg *)match->data;
+               dw9807_dev->idle_pos = cfg->idle_pos;
+               dw9807_dev->current_val = cfg->default_pos;
+       }
+
        v4l2_i2c_subdev_init(&dw9807_dev->sd, client, &dw9807_ops);
        dw9807_dev->sd.flags |= V4L2_SUBDEV_FL_HAS_DEVNODE;
        dw9807_dev->sd.internal_ops = &dw9807_int_ops;
@@ -203,7 +282,8 @@ static int dw9807_probe(struct i2c_clien
        if (rval < 0)
                goto err_cleanup;
 
-       pm_runtime_set_active(&client->dev);
+       if (!dw9807_dev->vdd)
+               pm_runtime_set_active(&client->dev);
        pm_runtime_enable(&client->dev);
        pm_runtime_idle(&client->dev);
 
@@ -237,15 +317,10 @@ static int __maybe_unused dw9807_vcm_sus
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
        struct dw9807_device *dw9807_dev = sd_to_dw9807_vcm(sd);
        const char tx_data[2] = { DW9807_CTL_ADDR, 0x01 };
-       int ret, val;
+       int ret;
 
-       for (val = dw9807_dev->current_val & ~(DW9807_CTRL_STEPS - 1);
-            val >= 0; val -= DW9807_CTRL_STEPS) {
-               ret = dw9807_set_dac(client, val);
-               if (ret)
-                       dev_err_once(dev, "%s I2C failure: %d", __func__, ret);
-               usleep_range(DW9807_CTRL_DELAY_US, DW9807_CTRL_DELAY_US + 10);
-       }
+       if (abs(dw9807_dev->current_val - dw9807_dev->idle_pos) > DW9807_CTRL_STEPS)
+               dw9807_ramp(client, dw9807_dev->current_val, dw9807_dev->idle_pos);
 
        /* Power down */
        ret = i2c_master_send(client, tx_data, sizeof(tx_data));
@@ -269,7 +344,7 @@ static int  __maybe_unused dw9807_vcm_re
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
        struct dw9807_device *dw9807_dev = sd_to_dw9807_vcm(sd);
        const char tx_data[2] = { DW9807_CTL_ADDR, 0x00 };
-       int ret, val;
+       int ret;
 
        /* Power on */
        ret = i2c_master_send(client, tx_data, sizeof(tx_data));
@@ -278,25 +353,11 @@ static int  __maybe_unused dw9807_vcm_re
                return ret;
        }
 
-       for (val = dw9807_dev->current_val % DW9807_CTRL_STEPS;
-            val < dw9807_dev->current_val + DW9807_CTRL_STEPS - 1;
-            val += DW9807_CTRL_STEPS) {
-               ret = dw9807_set_dac(client, val);
-               if (ret)
-                       dev_err_ratelimited(dev, "%s I2C failure: %d",
-                                               __func__, ret);
-               usleep_range(DW9807_CTRL_DELAY_US, DW9807_CTRL_DELAY_US + 10);
-       }
+       dw9807_ramp(client, dw9807_dev->idle_pos, dw9807_dev->current_val);
 
        return 0;
 }
 
-static const struct of_device_id dw9807_of_table[] = {
-       { .compatible = "dongwoon,dw9807-vcm" },
-       /* Compatibility for older firmware, NEVER USE THIS IN FIRMWARE! */
-       { .compatible = "dongwoon,dw9807" },
-       { /* sentinel */ }
-};
 MODULE_DEVICE_TABLE(of, dw9807_of_table);
 
 static const struct dev_pm_ops dw9807_pm_ops = {