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![Doug Anderson](/assets/img/avatar_default.png)
On ARM Chromebooks we have a few devices that are accessed by both the AP (the main "Application Processor") and the EC (the Embedded Controller). These are: * The battery (sbs-battery). * The power management unit tps65090. On the original Samsung ARM Chromebook these devices were on an I2C bus that was shared between the AP and the EC and arbitrated using some extranal GPIOs (see i2c-arb-gpio-challenge). The original arbitration scheme worked well enough but had some downsides: * It was nonstandard (not using standard I2C multimaster) * It only worked if the EC-AP communication was I2C * It was relatively hard to debug problems (hard to tell if i2c issues were caused by the EC, the AP, or some device on the bus). On the HP Chromebook 11 the design was changed to: * The AP/EC comms were still i2c, but the battery/tps65090 were no longer on the bus used for AP/EC communication. The battery was exposed to the AP through a limited i2c tunnel and tps65090 was exposed to the AP through a custom Linux driver. On the Samsung ARM Chromebook 2 the scheme is changed yet again, now: * The AP/EC comms are now using SPI for faster speeds. * The EC's i2c bus is exposed to the AP through a full i2c tunnel. The upstream "tegra124-venice2" uses the same scheme as the Samsung ARM Chromebook 2, though it has a different set of components on the other side of the bus. This driver supports the scheme used by the Samsung ARM Chromebook 2. Future patches to this driver could add support for the battery tunnel on the HP Chromebook 11 (and perhaps could even be used to access tps65090 on the HP Chromebook 11 instead of using a special driver, but I haven't researched that enough). Signed-off-by: Vincent Palatin <vpalatin@chromium.org> Signed-off-by: Simon Glass <sjg@chromium.org> Signed-off-by: Doug Anderson <dianders@chromium.org> Reviewed-by: Wolfram Sang <wsa@the-dreams.de> Signed-off-by: Lee Jones <lee.jones@linaro.org>
194 lines
4.6 KiB
C
194 lines
4.6 KiB
C
/*
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* ChromeOS EC multi-function device
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*
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* Copyright (C) 2012 Google, Inc
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*
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* This software is licensed under the terms of the GNU General Public
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* License version 2, as published by the Free Software Foundation, and
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* may be copied, distributed, and modified under those terms.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* The ChromeOS EC multi function device is used to mux all the requests
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* to the EC device for its multiple features: keyboard controller,
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* battery charging and regulator control, firmware update.
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*/
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#include <linux/interrupt.h>
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#include <linux/slab.h>
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#include <linux/module.h>
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#include <linux/mfd/core.h>
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#include <linux/mfd/cros_ec.h>
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#include <linux/mfd/cros_ec_commands.h>
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int cros_ec_prepare_tx(struct cros_ec_device *ec_dev,
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struct cros_ec_msg *msg)
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{
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uint8_t *out;
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int csum, i;
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BUG_ON(msg->out_len > EC_PROTO2_MAX_PARAM_SIZE);
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out = ec_dev->dout;
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out[0] = EC_CMD_VERSION0 + msg->version;
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out[1] = msg->cmd;
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out[2] = msg->out_len;
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csum = out[0] + out[1] + out[2];
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for (i = 0; i < msg->out_len; i++)
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csum += out[EC_MSG_TX_HEADER_BYTES + i] = msg->out_buf[i];
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out[EC_MSG_TX_HEADER_BYTES + msg->out_len] = (uint8_t)(csum & 0xff);
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return EC_MSG_TX_PROTO_BYTES + msg->out_len;
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}
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EXPORT_SYMBOL(cros_ec_prepare_tx);
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static int cros_ec_command_sendrecv(struct cros_ec_device *ec_dev,
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uint16_t cmd, void *out_buf, int out_len,
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void *in_buf, int in_len)
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{
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struct cros_ec_msg msg;
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msg.version = cmd >> 8;
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msg.cmd = cmd & 0xff;
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msg.out_buf = out_buf;
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msg.out_len = out_len;
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msg.in_buf = in_buf;
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msg.in_len = in_len;
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return ec_dev->command_xfer(ec_dev, &msg);
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}
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static int cros_ec_command_recv(struct cros_ec_device *ec_dev,
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uint16_t cmd, void *buf, int buf_len)
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{
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return cros_ec_command_sendrecv(ec_dev, cmd, NULL, 0, buf, buf_len);
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}
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static int cros_ec_command_send(struct cros_ec_device *ec_dev,
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uint16_t cmd, void *buf, int buf_len)
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{
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return cros_ec_command_sendrecv(ec_dev, cmd, buf, buf_len, NULL, 0);
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}
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static irqreturn_t ec_irq_thread(int irq, void *data)
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{
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struct cros_ec_device *ec_dev = data;
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if (device_may_wakeup(ec_dev->dev))
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pm_wakeup_event(ec_dev->dev, 0);
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blocking_notifier_call_chain(&ec_dev->event_notifier, 1, ec_dev);
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return IRQ_HANDLED;
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}
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static const struct mfd_cell cros_devs[] = {
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{
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.name = "cros-ec-keyb",
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.id = 1,
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.of_compatible = "google,cros-ec-keyb",
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},
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{
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.name = "cros-ec-i2c-tunnel",
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.id = 2,
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.of_compatible = "google,cros-ec-i2c-tunnel",
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},
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};
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int cros_ec_register(struct cros_ec_device *ec_dev)
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{
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struct device *dev = ec_dev->dev;
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int err = 0;
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BLOCKING_INIT_NOTIFIER_HEAD(&ec_dev->event_notifier);
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ec_dev->command_send = cros_ec_command_send;
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ec_dev->command_recv = cros_ec_command_recv;
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ec_dev->command_sendrecv = cros_ec_command_sendrecv;
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if (ec_dev->din_size) {
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ec_dev->din = devm_kzalloc(dev, ec_dev->din_size, GFP_KERNEL);
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if (!ec_dev->din)
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return -ENOMEM;
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}
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if (ec_dev->dout_size) {
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ec_dev->dout = devm_kzalloc(dev, ec_dev->dout_size, GFP_KERNEL);
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if (!ec_dev->dout)
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return -ENOMEM;
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}
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if (!ec_dev->irq) {
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dev_dbg(dev, "no valid IRQ: %d\n", ec_dev->irq);
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return err;
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}
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err = request_threaded_irq(ec_dev->irq, NULL, ec_irq_thread,
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IRQF_TRIGGER_LOW | IRQF_ONESHOT,
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"chromeos-ec", ec_dev);
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if (err) {
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dev_err(dev, "request irq %d: error %d\n", ec_dev->irq, err);
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return err;
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}
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err = mfd_add_devices(dev, 0, cros_devs,
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ARRAY_SIZE(cros_devs),
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NULL, ec_dev->irq, NULL);
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if (err) {
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dev_err(dev, "failed to add mfd devices\n");
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goto fail_mfd;
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}
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dev_info(dev, "Chrome EC (%s)\n", ec_dev->name);
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return 0;
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fail_mfd:
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free_irq(ec_dev->irq, ec_dev);
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return err;
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}
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EXPORT_SYMBOL(cros_ec_register);
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int cros_ec_remove(struct cros_ec_device *ec_dev)
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{
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mfd_remove_devices(ec_dev->dev);
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free_irq(ec_dev->irq, ec_dev);
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return 0;
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}
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EXPORT_SYMBOL(cros_ec_remove);
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#ifdef CONFIG_PM_SLEEP
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int cros_ec_suspend(struct cros_ec_device *ec_dev)
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{
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struct device *dev = ec_dev->dev;
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if (device_may_wakeup(dev))
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ec_dev->wake_enabled = !enable_irq_wake(ec_dev->irq);
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disable_irq(ec_dev->irq);
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ec_dev->was_wake_device = ec_dev->wake_enabled;
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return 0;
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}
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EXPORT_SYMBOL(cros_ec_suspend);
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int cros_ec_resume(struct cros_ec_device *ec_dev)
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{
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enable_irq(ec_dev->irq);
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if (ec_dev->wake_enabled) {
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disable_irq_wake(ec_dev->irq);
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ec_dev->wake_enabled = 0;
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}
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return 0;
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}
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EXPORT_SYMBOL(cros_ec_resume);
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#endif
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("ChromeOS EC core driver");
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