Hi Dmitry,

On Wed, Feb 13, 2013 at 12:02 PM, Dmitry Torokhov
[off-list ref] wrote:

Hi SImon,

On Tue, Feb 12, 2013 at 06:42:26PM -0800, Simon Glass wrote:

quoted

Use the key-matrix layer to interpret key scan information from the EC
and inject input based on the FDT-supplied key map. This driver registers
itself with the ChromeOS EC driver to perform communications.

Additional FDT bindings are provided to specify rows/columns and the
auto-repeat information.

Signed-off-by: Simon Glass <redacted>
Signed-off-by: Luigi Semenzato <redacted>
Signed-off-by: Vincent Palatin <redacted>
---
Changes in v2:
- Remove use of __devinit/__devexit
- Use function to read matrix-keypad parameters from DT
- Remove key autorepeat parameters from DT binding and driver
- Use unsigned int for rows/cols

Thanks for all the review comments.

quoted

 .../devicetree/bindings/input/cros-ec-keyb.txt     |  72 ++++
 drivers/input/keyboard/Kconfig                     |  12 +
 drivers/input/keyboard/Makefile                    |   1 +
 drivers/input/keyboard/cros_ec_keyb.c              | 394 +++++++++++++++++++++
 4 files changed, 479 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/input/cros-ec-keyb.txt
 create mode 100644 drivers/input/keyboard/cros_ec_keyb.c

diff --git a/Documentation/devicetree/bindings/input/cros-ec-keyb.txt b/Documentation/devicetree/bindings/input/cros-ec-keyb.txt
new file mode 100644
index 0000000..0f6355c
--- /dev/null
+++ b/Documentation/devicetree/bindings/input/cros-ec-keyb.txt

@@ -0,0 +1,72 @@
+ChromeOS EC Keyboard
+
+Google's ChromeOS EC Keyboard is a simple matrix keyboard implemented on
+a separate EC (Embedded Controller) device. It provides a message for reading
+key scans from the EC. These are then converted into keycodes for processing
+by the kernel.
+
+This binding is based on matrix-keymap.txt and extends/modifies it as follows:
+
+Required properties:
+- compatible: "google,cros-ec-keyb"
+
+Optional properties:
+- google,needs-ghost-filter: True to enable a ghost filter for the matrix
+keyboard. This is recommended if the EC does not have its own logic or
+hardware for this.
+
+
+Example:
+
+cros-ec-keyb {
+     compatible = "google,cros-ec-keyb";
+     keypad,num-rows = <8>;
+     keypad,num-columns = <13>;
+     google,needs-ghost-filter;
+     /*
+      * Keymap entries take the form of 0xRRCCKKKK where
+      * RR=Row CC=Column KKKK=Key Code
+      * The values below are for a US keyboard layout and
+      * are taken from the Linux driver. Note that the
+      * 102ND key is not used for US keyboards.
+      */
+     linux,keymap = <
+             /* CAPSLCK F1         B          F10     */
+             0x0001003a 0x0002003b 0x00030030 0x00040044
+             /* N       =          R_ALT      ESC     */
+             0x00060031 0x0008000d 0x000a0064 0x01010001
+             /* F4      G          F7         H       */
+             0x0102003e 0x01030022 0x01040041 0x01060023
+             /* '       F9         BKSPACE    L_CTRL  */
+             0x01080028 0x01090043 0x010b000e 0x0200001d
+             /* TAB     F3         T          F6      */
+             0x0201000f 0x0202003d 0x02030014 0x02040040
+             /* ]       Y          102ND      [       */
+             0x0205001b 0x02060015 0x02070056 0x0208001a
+             /* F8      GRAVE      F2         5       */
+             0x02090042 0x03010029 0x0302003c 0x03030006
+             /* F5      6          -          \       */
+             0x0304003f 0x03060007 0x0308000c 0x030b002b
+             /* R_CTRL  A          D          F       */
+             0x04000061 0x0401001e 0x04020020 0x04030021
+             /* S       K          J          ;       */
+             0x0404001f 0x04050025 0x04060024 0x04080027
+             /* L       ENTER      Z          C       */
+             0x04090026 0x040b001c 0x0501002c 0x0502002e
+             /* V       X          ,          M       */
+             0x0503002f 0x0504002d 0x05050033 0x05060032
+             /* L_SHIFT /          .          SPACE   */
+             0x0507002a 0x05080035 0x05090034 0x050B0039
+             /* 1       3          4          2       */
+             0x06010002 0x06020004 0x06030005 0x06040003
+             /* 8       7          0          9       */
+             0x06050009 0x06060008 0x0608000b 0x0609000a
+             /* L_ALT   DOWN       RIGHT      Q       */
+             0x060a0038 0x060b006c 0x060c006a 0x07010010
+             /* E       R          W          I       */
+             0x07020012 0x07030013 0x07040011 0x07050017
+             /* U       R_SHIFT    P          O       */
+             0x07060016 0x07070036 0x07080019 0x07090018
+             /* UP      LEFT    */
+             0x070b0067 0x070c0069>;
+};

diff --git a/drivers/input/keyboard/Kconfig b/drivers/input/keyboard/Kconfig
index 078305e..3a70be7 100644
--- a/drivers/input/keyboard/Kconfig
+++ b/drivers/input/keyboard/Kconfig

@@ -628,4 +628,16 @@ config KEYBOARD_W90P910
        To compile this driver as a module, choose M here: the
        module will be called w90p910_keypad.

+config KEYBOARD_CROS_EC
+     tristate "ChromeOS EC keyboard"
+     select INPUT_MATRIXKMAP
+     select MFD_CROS_EC

Is this select safe? I.e. does MFD_CROS_EC depend on anything else?

I'll remove it, since it isn't required, and it's true that it does
need other things.

quoted

+     help
+       Say Y here to enable the matrix keyboard used by ChromeOS devices
+       and implemented on the ChromeOS EC. You must enable one bus option
+       (MFD_CROS_EC_I2C or MFD_CROS_EC_SPI) to use this.
+
+       To compile this driver as a module, choose M here: the
+       module will be called cros_ec_keyb.
+
 endif

diff --git a/drivers/input/keyboard/Makefile b/drivers/input/keyboard/Makefile
index 49b1645..0c43e8c 100644
--- a/drivers/input/keyboard/Makefile
+++ b/drivers/input/keyboard/Makefile

@@ -11,6 +11,7 @@ obj-$(CONFIG_KEYBOARD_AMIGA)                += amikbd.o
 obj-$(CONFIG_KEYBOARD_ATARI)         += atakbd.o
 obj-$(CONFIG_KEYBOARD_ATKBD)         += atkbd.o
 obj-$(CONFIG_KEYBOARD_BFIN)          += bf54x-keys.o
+obj-$(CONFIG_KEYBOARD_CROS_EC)               += cros_ec_keyb.o
 obj-$(CONFIG_KEYBOARD_DAVINCI)               += davinci_keyscan.o
 obj-$(CONFIG_KEYBOARD_EP93XX)                += ep93xx_keypad.o
 obj-$(CONFIG_KEYBOARD_GOLDFISH_EVENTS)       += goldfish_events.o

diff --git a/drivers/input/keyboard/cros_ec_keyb.c b/drivers/input/keyboard/cros_ec_keyb.c
new file mode 100644
index 0000000..43e5be2
--- /dev/null
+++ b/drivers/input/keyboard/cros_ec_keyb.c

@@ -0,0 +1,394 @@
+/*
+ * ChromeOS EC keyboard driver
+ *
+ * Copyright (C) 2012 Google, Inc
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ * This driver uses the Chrome OS EC byte-level message-based protocol for
+ * communicating the keyboard state (which keys are pressed) from a keyboard EC
+ * to the AP over some bus (such as i2c, lpc, spi).  The EC does debouncing,
+ * but everything else (including deghosting) is done here.  The main
+ * motivation for this is to keep the EC firmware as simple as possible, since
+ * it cannot be easily upgraded and EC flash/IRAM space is relatively
+ * expensive.
+ */
+
+#include <linux/module.h>
+#include <linux/i2c.h>
+#include <linux/input.h>
+#include <linux/kernel.h>
+#include <linux/notifier.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/input/matrix_keypad.h>
+#include <linux/mfd/cros_ec.h>
+#include <linux/mfd/cros_ec_commands.h>
+
+/*
+ * @rows: Number of rows in the keypad
+ * @cols: Number of columns in the keypad
+ * @row_shift: log2 or number of rows, rounded up
+ * @keymap_data: Matrix keymap data used to convert to keyscan values
+ * @ghost_filter: true to enable the matrix key-ghosting filter
+ * @old_state: Previous state of the keyboard matrix (used to calc deltas)
+ * @dev: Device pointer
+ * @idev: Input device
+ * @ec: Top level ChromeOS device to use to talk to EC
+ * @event_notifier: interrupt event notifier for transport devices
+ * @wake_notifier: wake notfier for client devices (e.g. keyboard). This
+ *   indicates to sub-drivers that we have woken up from resume but we
+ *   were not a wakeup source.
+ */
+struct cros_ec_keyb {
+     unsigned int rows;
+     unsigned int cols;
+     int row_shift;
+     const struct matrix_keymap_data *keymap_data;
+     bool ghost_filter;
+     /*
+      * old_state[matrix code] is 1 when the most recent (valid)
+      * communication with the keyboard indicated that the key at row/col
+      * was in the pressed state.
+      */
+     uint8_t *old_state;
+
+     struct device *dev;
+     struct input_dev *idev;
+     struct cros_ec_device *ec;
+     struct notifier_block notifier;
+     struct notifier_block wake_notifier;
+};
+
+
+/*
+ * Sends a single key event to the input layer.
+ */
+static inline void cros_ec_keyb_send_key_event(struct cros_ec_keyb *ckdev,
+                             int row, int col, int pressed)
+{
+     struct input_dev *idev = ckdev->idev;
+     int code = MATRIX_SCAN_CODE(row, col, ckdev->row_shift);
+     const unsigned short *keycodes = idev->keycode;
+
+     input_report_key(idev, keycodes[code], pressed);
+}
+
+/*
+ * Returns true when there is at least one combination of pressed keys that
+ * results in ghosting.
+ */
+static bool cros_ec_keyb_has_ghosting(struct cros_ec_keyb *ckdev, uint8_t *buf)
+{
+     int col, row;
+     int mask;
+     int pressed_in_row[ckdev->rows];
+     int row_has_teeth[ckdev->rows];
+
+     memset(pressed_in_row, '\0', sizeof(pressed_in_row));
+     memset(row_has_teeth, '\0', sizeof(row_has_teeth));
+     /*
+      * Ghosting happens if for any pressed key X there are other keys
+      * pressed both in the same row and column of X as, for instance,
+      * in the following diagram:
+      *
+      * . . Y . g .
+      * . . . . . .
+      * . . . . . .
+      * . . X . Z .
+      *
+      * In this case only X, Y, and Z are pressed, but g appears to be
+      * pressed too (see Wikipedia).
+      *
+      * We can detect ghosting in a single pass (*) over the keyboard state
+      * by maintaining two arrays.  pressed_in_row counts how many pressed
+      * keys we have found in a row.  row_has_teeth is true if any of the
+      * pressed keys for this row has other pressed keys in its column.  If
+      * at any point of the scan we find that a row has multiple pressed
+      * keys, and at least one of them is at the intersection with a column
+      * with multiple pressed keys, we're sure there is ghosting.
+      * Conversely, if there is ghosting, we will detect such situation for
+      * at least one key during the pass.
+      *
+      * (*) This looks linear in the number of keys, but it's not.  We can
+      * cheat because the number of rows is small.
+      */
+     for (row = 0; row < ckdev->rows; row++) {
+             mask = 1 << row;
+             for (col = 0; col < ckdev->cols; col++) {
+                     if (buf[col] & mask) {
+                             pressed_in_row[row] += 1;

Just ++ please.

Done

quoted

+                             row_has_teeth[row] |= buf[col] & ~mask;
+                             if (pressed_in_row[row] > 1 &&
+                                 row_has_teeth[row]) {
+                                     /* ghosting */
+                                     dev_dbg(ckdev->dev,
+                                             "ghost found at: r%d c%d,"
+                                             " pressed %d, teeth 0x%x\n",

Please do not break message strings even if they push you over 80 columns.

Done

quoted

+                                             row, col, pressed_in_row[row],
+                                             row_has_teeth[row]);
+                                     return true;
+                             }

I am confused why you need pressed_in_row and row_has_teeth arrays as
you are working with one row at a time.

Hmmm I never did quite grok that code. I can't see why we need an
array, so have changed it.

Also, can we move inner loop into a separate function?

Done

quoted

+                     }
+             }
+     }
+     return false;
+}
+
+/*
+ * Compares the new keyboard state to the old one and produces key
+ * press/release events accordingly.  The keyboard state is 13 bytes (one byte
+ * per column)
+ */
+static void cros_ec_keyb_process(struct cros_ec_keyb *ckdev,
+                      uint8_t *kb_state, int len)
+{
+     int col, row;
+     int new_state;
+     int num_cols;
+
+     num_cols = len;
+
+     if (ckdev->ghost_filter && cros_ec_keyb_has_ghosting(ckdev, kb_state)) {
+             /*
+              * Simple-minded solution: ignore this state. The obvious
+              * improvement is to only ignore changes to keys involved in
+              * the ghosting, but process the other changes.
+              */
+             dev_dbg(ckdev->dev, "ghosting found\n");
+             return;
+     }
+
+     for (col = 0; col < ckdev->cols; col++) {
+             for (row = 0; row < ckdev->rows; row++) {
+                     int code = MATRIX_SCAN_CODE(row, col, ckdev->row_shift);
+
+                     new_state = kb_state[col] & (1 << row);
+                     if (!!new_state != ckdev->old_state[code]) {
+                             dev_dbg(ckdev->dev,
+                                     "changed: [r%d c%d]: byte %02x\n",
+                                     row, col, new_state);
+                     }
+                     if (new_state && !ckdev->old_state[code]) {
+                             /* key press */
+                             cros_ec_keyb_send_key_event(ckdev, row, col, 1);
+                             ckdev->old_state[code] = 1;
+                     } else if (!new_state && ckdev->old_state[code]) {
+                             /* key release */
+                             cros_ec_keyb_send_key_event(ckdev, row, col, 0);
+                             ckdev->old_state[code] = 0;
+                     }

Should not all of the above be:

                        if (!!new_state != test_bit(code, dev->key)) {
                                dev_dbg(ckdev->dev,
                                        "changed: [r%d c%d]: byte %02x\n",
                                        row, col, new_state);

                                input_report_key(idev, keycodes[code], new_state);
                        }

and yo can get rid of old_state altogether?

That's cool. Done.

quoted

+             }
+     }
+     input_sync(ckdev->idev);
+}
+
+static int cros_ec_keyb_open(struct input_dev *dev)
+{
+     struct cros_ec_keyb *ckdev = input_get_drvdata(dev);
+     int ret;
+
+     ret = blocking_notifier_chain_register(&ckdev->ec->event_notifier,
+                                             &ckdev->notifier);
+     if (ret)
+             return ret;
+     ret = blocking_notifier_chain_register(&ckdev->ec->wake_notifier,
+                                             &ckdev->wake_notifier);
+     if (ret) {
+             blocking_notifier_chain_unregister(
+                     &ckdev->ec->event_notifier, &ckdev->notifier);
+             return ret;
+     }
+
+     return 0;
+}
+
+static void cros_ec_keyb_close(struct input_dev *dev)
+{
+     struct cros_ec_keyb *ckdev = input_get_drvdata(dev);
+
+     blocking_notifier_chain_unregister(&ckdev->ec->event_notifier,
+                                        &ckdev->notifier);
+     blocking_notifier_chain_unregister(&ckdev->ec->wake_notifier,
+                                        &ckdev->wake_notifier);

Why is this done via a notifier instead of regular resume method?

Because we only call the notifer in resume when we were not waking on
a keyboard event. We use it to flush the keyboard. It was a late
change so there might be a better way, but this driver does not have a
resume handler.

quoted

+}
+
+static int cros_ec_keyb_get_state(struct cros_ec_keyb *ckdev, uint8_t *kb_state)
+{
+     return ckdev->ec->command_recv(ckdev->ec, EC_CMD_MKBP_STATE,
+                                       kb_state, ckdev->cols);
+}
+
+static int cros_ec_keyb_work(struct notifier_block *nb,
+                  unsigned long state, void *_notify)
+{
+     int ret;
+     struct cros_ec_keyb *ckdev = container_of(nb, struct cros_ec_keyb,
+                                                 notifier);
+     uint8_t kb_state[ckdev->cols];
+
+     ret = cros_ec_keyb_get_state(ckdev, kb_state);
+     if (ret >= 0)
+             cros_ec_keyb_process(ckdev, kb_state, ret);
+
+     return NOTIFY_DONE;
+}
+
+/* On resume, clear any keys in the buffer */
+static int cros_ec_keyb_clear_keyboard(struct notifier_block *nb,
+                            unsigned long state, void *_notify)
+{
+     struct cros_ec_keyb *ckdev = container_of(nb, struct cros_ec_keyb,
+                                                 wake_notifier);
+     uint8_t old_state[ckdev->cols];
+     uint8_t new_state[ckdev->cols];
+     unsigned long duration;
+     int i, ret;
+
+     /*
+      * Keep reading until we see that the scan state does not change.
+      * That indicates that we are done.
+      *
+      * Assume that the EC keyscan buffer is at most 32 deep.
+      */
+     duration = jiffies;
+     ret = cros_ec_keyb_get_state(ckdev, new_state);
+     for (i = 1; !ret && i < 32; i++) {
+             memcpy(old_state, new_state, sizeof(old_state));
+             ret = cros_ec_keyb_get_state(ckdev, new_state);
+             if (0 == memcmp(old_state, new_state, sizeof(old_state)))
+                     break;
+     }
+     duration = jiffies - duration;
+     dev_info(ckdev->dev, "Discarded %d keyscan(s) in %dus\n", i,
+             jiffies_to_usecs(duration));
+
+     return 0;
+}
+
+static const struct of_device_id cros_ec_kbc_of_match[] = {
+     { .compatible = "google,cros-ec-keyb", },
+     { },
+};
+
+static int cros_ec_keyb_probe(struct platform_device *pdev)
+{
+     struct cros_ec_device *ec = dev_get_drvdata(pdev->dev.parent);
+     struct device *dev = ec->dev;
+     struct cros_ec_keyb *ckdev = NULL;
+     struct input_dev *idev = NULL;
+     struct device_node *np;
+     int err;
+
+     np = of_find_matching_node(NULL, cros_ec_kbc_of_match);

And if we don't find it?

Added error checking.

quoted

+
+     ckdev = kzalloc(sizeof(*ckdev), GFP_KERNEL);
+     if (!ckdev) {
+             dev_err(dev, "cannot allocate memory for ckdev\n");
+             return -ENOMEM;
+     }
+     pdev->dev.of_node = np;

Huh? I'd expect the platform device be fully set up (including DT data)
before the driver is called.

This is a child of the mfd driver cros_ec, so I don't think that
works. Or maybe I'm just not sure how to plumb it in so it is
automatic. Or maybe I just need to add the id to the device info
below?

quoted

+     err = matrix_keypad_parse_of_params(&pdev->dev, &ckdev->rows,
+                                         &ckdev->cols);
+     if (err)
+             goto fail_alloc_dev;
+
+     idev = input_allocate_device();
+     if (!idev) {
+             err = -ENOMEM;
+             dev_err(dev, "cannot allocate memory for input device\n");
+             goto fail_alloc_dev;
+     }
+
+     ckdev->ec = ec;
+     ckdev->notifier.notifier_call = cros_ec_keyb_work;
+     ckdev->wake_notifier.notifier_call = cros_ec_keyb_clear_keyboard;
+     ckdev->dev = dev;
+     dev_set_drvdata(&pdev->dev, ckdev);
+
+     idev->name = ec->get_name(ec);
+     idev->phys = ec->get_phys_name(ec);
+     __set_bit(EV_REP, idev->evbit);
+
+     idev->id.bustype = BUS_VIRTUAL;
+     idev->id.version = 1;
+     idev->id.product = 0;
+     idev->dev.parent = &pdev->dev;
+     idev->open = cros_ec_keyb_open;
+     idev->close = cros_ec_keyb_close;
+
+     ckdev->ghost_filter = of_property_read_bool(np,
+                                     "google,needs-ghost-filter");
+
+     err = matrix_keypad_build_keymap(NULL, NULL, ckdev->rows, ckdev->cols,
+                                      NULL, idev);
+     if (err) {
+             dev_err(dev, "cannot build key matrix\n");
+             goto fail_matrix;
+     }
+
+     ckdev->row_shift = get_count_order(ckdev->cols);
+     ckdev->old_state = kzalloc(idev->keycodemax, GFP_KERNEL);
+     if (!ckdev->old_state) {
+             dev_err(dev, "Cannot allocate memory for old_state\n");
+             err = -ENOMEM;
+             goto fail_old_state;
+     }

Not needed I believe.

Dropped.

quoted

+
+     input_set_capability(idev, EV_MSC, MSC_SCAN);
+     input_set_drvdata(idev, ckdev);
+     ckdev->idev = idev;
+     err = input_register_device(ckdev->idev);
+     if (err) {
+             dev_err(dev, "cannot register input device\n");
+             goto fail_register;
+     }
+
+     return 0;
+
+fail_register:
+     kfree(ckdev->old_state);
+fail_old_state:
+     kfree(idev->keycode);
+fail_matrix:
+     input_free_device(idev);
+fail_alloc_dev:
+     kfree(ckdev);
+     return err;
+}
+
+static int cros_ec_keyb_remove(struct platform_device *pdev)
+{
+     struct cros_ec_keyb *ckdev = dev_get_drvdata(&pdev->dev);

platform_get_drvdata() please.

Done

quoted

+     struct input_dev *idev = ckdev->idev;
+
+     /* I believe we leak a matrix_keymap here */

How? It is devm-managed.

Original code might pre-date that. Removed comment.

quoted

+     input_unregister_device(idev);
+     kfree(ckdev->old_state);
+     kfree(idev->keycode);

And since it is devm-managed you should not free it yourself. Actually
idev is most likely gone at this point already.

Yes, done.

quoted

+     input_free_device(idev);

Do not call input_free_device() after input_unregister_device().

Done

quoted

+     kfree(ckdev);
+
+     return 0;
+}
+
+static struct platform_driver cros_ec_keyb_driver = {
+     .probe = cros_ec_keyb_probe,
+     .remove = cros_ec_keyb_remove,
+     .driver = {
+             .name = "cros-ec-keyb",
+     },
+};
+
+module_platform_driver(cros_ec_keyb_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("ChromeOS EC keyboard driver");
+MODULE_ALIAS("platform:cros-ec-keyb");
--
1.8.1

Thanks.

--
Dmitry

I'll send a new version so that the above is done, at least.

Regards,
Simon