Patchwork [v2,06/17] Platform: OLPC: Add XO-1.75 EC driver

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Submitter Lubomir Rintel
Date Nov. 16, 2018, 4:23 p.m.
Message ID <20181116162403.49854-7-lkundrak@v3.sk>
Download mbox | patch
Permalink /patch/658719/
State New
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Comments

Lubomir Rintel - Nov. 16, 2018, 4:23 p.m.
It's based off the driver from the OLPC kernel sources. Somewhat
modernized and cleaned up, for better or worse.

Modified to plug into the olpc-ec driver infrastructure (so that battery
interface and debugfs could be reused) and the SPI slave framework.

Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>

---
Changes since v1:
- Cosmetic style changes; whitespace, ordering of declarations and
  #includes, remoted extra comas from sentinels
- Count the terminating NUL in LOG_BUF_SIZE
- Make olpc_xo175_ec_is_valid_cmd() return -EINVAL instead of -1
  on error
- Spell keyboard/touchpad in full for CHAN_KEYBOARD/TOUCHPAD messages
- Use a #define for PM wakeup processing time
- Log a message on unknown event
- Escape logging payload with %*pE
- Replace an open-coded min()
- Correct an error code on short read
- replaced PM callback #ifdefs with __maybe_unusedm SET_RUNTIME_PM_OPS
  and SET_NOIRQ_SYSTEM_SLEEP_PM_OPS
- dev_get_drvdata() instead of a round-trip through platform device
- s/unsigned char x/u8 x/ in olpc_xo175_ec_resume()
- Use GENMASK() instead of 0xffff for the event mask
- Replace cmd tx/resp rx buffers with structures
- Turned suspend hint arguments into a struct, and tidied up the comment

Basically all of the above is based on the review by Andy Shevchenko.

 drivers/platform/olpc/Kconfig         |  15 +
 drivers/platform/olpc/Makefile        |   1 +
 drivers/platform/olpc/olpc-xo175-ec.c | 763 ++++++++++++++++++++++++++
 3 files changed, 779 insertions(+)
 create mode 100644 drivers/platform/olpc/olpc-xo175-ec.c
Darren Hart - Dec. 2, 2018, 11:13 p.m.
On Fri, Nov 16, 2018 at 05:23:52PM +0100, Lubomir Rintel wrote:
> It's based off the driver from the OLPC kernel sources. Somewhat
> modernized and cleaned up, for better or worse.
> 
> Modified to plug into the olpc-ec driver infrastructure (so that battery
> interface and debugfs could be reused) and the SPI slave framework.
> 
> Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
> 

Hi Lubomir,

You asked for some tips on how to incorporate the changes in a patch
series like this.

Keep in mind that each patch should create an independent small
functional change. This makes it easier to review the patch and verify
that what you said you were going to do matches what the patch does. For
example, if you separate out the style, whitespace, ordering of
declarations into an initial first patch, then all that noise is removed
when the reviewer goes to check to implementation of one of the features
below.

This is a large patch, and should most certainly be broken up into
several smaller patches. Do cleanups first, followed by functional
changes. This ordering ensure that when a "git blame" is used in the
future to understand why a given line is what it is, the first hit will
be a functional change, and not a cleanup.

> ---
> Changes since v1:
> - Cosmetic style changes; whitespace, ordering of declarations and
>   #includes, remoted extra comas from sentinels

Please make this a separate change, possibly more than one, depending on
how many of these there are. This will reduce the size of the subsequent
patches, making them easier to review.

> - Count the terminating NUL in LOG_BUF_SIZE
> - Make olpc_xo175_ec_is_valid_cmd() return -EINVAL instead of -1
>   on error
> - Spell keyboard/touchpad in full for CHAN_KEYBOARD/TOUCHPAD messages
> - Use a #define for PM wakeup processing time
> - Log a message on unknown event
> - Escape logging payload with %*pE
> - Replace an open-coded min()
> - Correct an error code on short read
> - replaced PM callback #ifdefs with __maybe_unusedm SET_RUNTIME_PM_OPS
>   and SET_NOIRQ_SYSTEM_SLEEP_PM_OPS
> - dev_get_drvdata() instead of a round-trip through platform device
> - s/unsigned char x/u8 x/ in olpc_xo175_ec_resume()
> - Use GENMASK() instead of 0xffff for the event mask
> - Replace cmd tx/resp rx buffers with structures
> - Turned suspend hint arguments into a struct, and tidied up the comment

Just from these comments, each of these could be a separate patch. You
can group related things together, or those that change the same line or
function for example. Order them with cleanups / non-functional-changes
first, followed by functional changes.

> 
> Basically all of the above is based on the review by Andy Shevchenko.

Andy, what was your intent for Lubomir here? From the above, this looks
like it should be several patches to me.

Thanks,
Andy Shevchenko - Dec. 3, 2018, 7:54 a.m.
On Mon, Dec 3, 2018 at 1:13 AM Darren Hart <dvhart@infradead.org> wrote:
> On Fri, Nov 16, 2018 at 05:23:52PM +0100, Lubomir Rintel wrote:
> > It's based off the driver from the OLPC kernel sources. Somewhat
> > modernized and cleaned up, for better or worse.
> >
> > Modified to plug into the olpc-ec driver infrastructure (so that battery
> > interface and debugfs could be reused) and the SPI slave framework.

> > - Count the terminating NUL in LOG_BUF_SIZE
> > - Make olpc_xo175_ec_is_valid_cmd() return -EINVAL instead of -1
> >   on error
> > - Spell keyboard/touchpad in full for CHAN_KEYBOARD/TOUCHPAD messages
> > - Use a #define for PM wakeup processing time
> > - Log a message on unknown event
> > - Escape logging payload with %*pE
> > - Replace an open-coded min()
> > - Correct an error code on short read
> > - replaced PM callback #ifdefs with __maybe_unusedm SET_RUNTIME_PM_OPS
> >   and SET_NOIRQ_SYSTEM_SLEEP_PM_OPS
> > - dev_get_drvdata() instead of a round-trip through platform device
> > - s/unsigned char x/u8 x/ in olpc_xo175_ec_resume()
> > - Use GENMASK() instead of 0xffff for the event mask
> > - Replace cmd tx/resp rx buffers with structures
> > - Turned suspend hint arguments into a struct, and tidied up the comment
>
> Just from these comments, each of these could be a separate patch. You
> can group related things together, or those that change the same line or
> function for example. Order them with cleanups / non-functional-changes
> first, followed by functional changes.
>
> >
> > Basically all of the above is based on the review by Andy Shevchenko.
>
> Andy, what was your intent for Lubomir here? From the above, this looks
> like it should be several patches to me.

This is a new module, I don't see why it can't be one patch. For the
existing code I agree with you.

Patch

diff --git a/drivers/platform/olpc/Kconfig b/drivers/platform/olpc/Kconfig
index 7b736c9e67ac..7c643d24ad0f 100644
--- a/drivers/platform/olpc/Kconfig
+++ b/drivers/platform/olpc/Kconfig
@@ -9,3 +9,18 @@  config OLPC
 	help
 	  Add support for detecting the unique features of the OLPC
 	  XO hardware.
+
+if OLPC
+
+config OLPC_XO175_EC
+	tristate "OLPC XO 1.75 Embedded Controller"
+	depends on ARCH_MMP || COMPILE_TEST
+	select SPI_SLAVE
+	help
+	  Include support for the OLPC XO Embedded Controller (EC). The EC
+	  provides various platform services, including support for the power,
+	  button, restart, shutdown and battery charging status.
+
+	  Unless you have an OLPC XO laptop, you will want to say N.
+
+endif
diff --git a/drivers/platform/olpc/Makefile b/drivers/platform/olpc/Makefile
index dc8b26bc7209..5b43f383289e 100644
--- a/drivers/platform/olpc/Makefile
+++ b/drivers/platform/olpc/Makefile
@@ -2,3 +2,4 @@ 
 # OLPC XO platform-specific drivers
 #
 obj-$(CONFIG_OLPC)		+= olpc-ec.o
+obj-$(CONFIG_OLPC_XO175_EC)	+= olpc-xo175-ec.o
diff --git a/drivers/platform/olpc/olpc-xo175-ec.c b/drivers/platform/olpc/olpc-xo175-ec.c
new file mode 100644
index 000000000000..74db06bacc44
--- /dev/null
+++ b/drivers/platform/olpc/olpc-xo175-ec.c
@@ -0,0 +1,763 @@ 
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for the OLPC XO-1.75 Embedded Controller.
+ *
+ * The EC protocol is documented at:
+ * http://wiki.laptop.org/go/XO_1.75_HOST_to_EC_Protocol
+ *
+ * Copyright (C) 2010 One Laptop per Child Foundation.
+ * Copyright (C) 2018 Lubomir Rintel <lkundrak@v3.sk>
+ */
+
+#include <linux/completion.h>
+#include <linux/ctype.h>
+#include <linux/delay.h>
+#include <linux/gpio/consumer.h>
+#include <linux/input.h>
+#include <linux/kfifo.h>
+#include <linux/module.h>
+#include <linux/olpc-ec.h>
+#include <linux/platform_device.h>
+#include <linux/power_supply.h>
+#include <linux/reboot.h>
+#include <linux/slab.h>
+#include <linux/spinlock.h>
+#include <linux/spi/spi.h>
+#include <asm/system_misc.h>
+
+struct ec_cmd_t {
+	u8 cmd;
+	u8 bytes_returned;
+};
+
+enum ec_chan_t {
+	CHAN_NONE = 0,
+	CHAN_SWITCH,
+	CHAN_CMD_RESP,
+	CHAN_KEYBOARD,
+	CHAN_TOUCHPAD,
+	CHAN_EVENT,
+	CHAN_DEBUG,
+	CHAN_CMD_ERROR,
+};
+
+/*
+ * EC events
+ */
+#define EVENT_AC_CHANGE			1  /* AC plugged/unplugged */
+#define EVENT_BATTERY_STATUS		2  /* Battery low/full/error/gone */
+#define EVENT_BATTERY_CRITICAL		3  /* Battery critical voltage */
+#define EVENT_BATTERY_SOC_CHANGE	4  /* 1% SOC Change */
+#define EVENT_BATTERY_ERROR		5  /* Abnormal error, query for cause */
+#define EVENT_POWER_PRESSED		6  /* Power button was pressed */
+#define EVENT_POWER_PRESS_WAKE		7  /* Woken up with a power button */
+#define EVENT_TIMED_HOST_WAKE		8  /* Host wake timer */
+#define EVENT_OLS_HIGH_LIMIT		9  /* OLS crossed dark threshold */
+#define EVENT_OLS_LOW_LIMIT		10 /* OLS crossed light threshold */
+
+/*
+ * EC commands
+ * (from http://dev.laptop.org/git/users/rsmith/ec-1.75/tree/ec_cmd.h)
+ */
+#define CMD_GET_API_VERSION		0x08 /* out: u8 */
+#define CMD_READ_VOLTAGE		0x10 /* out: u16, *9.76/32, mV */
+#define CMD_READ_CURRENT		0x11 /* out: s16, *15.625/120, mA */
+#define CMD_READ_ACR			0x12 /* out: s16, *6250/15, uAh */
+#define CMD_READ_BATT_TEMPERATURE	0x13 /* out: u16, *100/256, deg C */
+#define CMD_READ_AMBIENT_TEMPERATURE	0x14 /* unimplemented, no hardware */
+#define CMD_READ_BATTERY_STATUS		0x15 /* out: u8, bitmask */
+#define CMD_READ_SOC			0x16 /* out: u8, percentage */
+#define CMD_READ_GAUGE_ID		0x17 /* out: u8 * 8 */
+#define CMD_READ_GAUGE_DATA		0x18 /* in: u8 addr, out: u8 data */
+#define CMD_READ_BOARD_ID		0x19 /* out: u16 (platform id) */
+#define CMD_READ_BATT_ERR_CODE		0x1f /* out: u8, error bitmask */
+#define CMD_SET_DCON_POWER		0x26 /* in: u8 */
+#define CMD_RESET_EC			0x28 /* none */
+#define CMD_READ_BATTERY_TYPE		0x2c /* out: u8 */
+#define CMD_SET_AUTOWAK			0x33 /* out: u8 */
+#define CMD_SET_EC_WAKEUP_TIMER		0x36 /* in: u32, out: ? */
+#define CMD_READ_EXT_SCI_MASK		0x37 /* ? */
+#define CMD_WRITE_EXT_SCI_MASK		0x38 /* ? */
+#define CMD_CLEAR_EC_WAKEUP_TIMER	0x39 /* none */
+#define CMD_ENABLE_RUNIN_DISCHARGE	0x3B /* none */
+#define CMD_DISABLE_RUNIN_DISCHARGE	0x3C /* none */
+#define CMD_READ_MPPT_ACTIVE		0x3d /* out: u8 */
+#define CMD_READ_MPPT_LIMIT		0x3e /* out: u8 */
+#define CMD_SET_MPPT_LIMIT		0x3f /* in: u8 */
+#define CMD_DISABLE_MPPT		0x40 /* none */
+#define CMD_ENABLE_MPPT			0x41 /* none */
+#define CMD_READ_VIN			0x42 /* out: u16 */
+#define CMD_EXT_SCI_QUERY		0x43 /* ? */
+#define RSP_KEYBOARD_DATA		0x48 /* ? */
+#define RSP_TOUCHPAD_DATA		0x49 /* ? */
+#define CMD_GET_FW_VERSION		0x4a /* out: u8 * 16 */
+#define CMD_POWER_CYCLE			0x4b /* none */
+#define CMD_POWER_OFF			0x4c /* none */
+#define CMD_RESET_EC_SOFT		0x4d /* none */
+#define CMD_READ_GAUGE_U16		0x4e /* ? */
+#define CMD_ENABLE_MOUSE		0x4f /* ? */
+#define CMD_ECHO			0x52 /* in: u8 * 5, out: u8 * 5 */
+#define CMD_GET_FW_DATE			0x53 /* out: u8 * 16 */
+#define CMD_GET_FW_USER			0x54 /* out: u8 * 16 */
+#define CMD_TURN_OFF_POWER		0x55 /* none (same as 0x4c) */
+#define CMD_READ_OLS			0x56 /* out: u16 */
+#define CMD_OLS_SMT_LEDON		0x57 /* none */
+#define CMD_OLS_SMT_LEDOFF		0x58 /* none */
+#define CMD_START_OLS_ASSY		0x59 /* none */
+#define CMD_STOP_OLS_ASSY		0x5a /* none */
+#define CMD_OLS_SMTTEST_STOP		0x5b /* none */
+#define CMD_READ_VIN_SCALED		0x5c /* out: u16 */
+#define CMD_READ_BAT_MIN_W		0x5d /* out: u16 */
+#define CMD_READ_BAR_MAX_W		0x5e /* out: u16 */
+#define CMD_RESET_BAT_MINMAX_W		0x5f /* none */
+#define CMD_READ_LOCATION		0x60 /* in: u16 addr, out: u8 data */
+#define CMD_WRITE_LOCATION		0x61 /* in: u16 addr, u8 data */
+#define CMD_KEYBOARD_CMD		0x62 /* in: u8, out: ? */
+#define CMD_TOUCHPAD_CMD		0x63 /* in: u8, out: ? */
+#define CMD_GET_FW_HASH			0x64 /* out: u8 * 16 */
+#define CMD_SUSPEND_HINT		0x65 /* in: u8 */
+#define CMD_ENABLE_WAKE_TIMER		0x66 /* in: u8 */
+#define CMD_SET_WAKE_TIMER		0x67 /* in: 32 */
+#define CMD_ENABLE_WAKE_AUTORESET	0x68 /* in: u8 */
+#define CMD_OLS_SET_LIMITS		0x69 /* in: u16, u16 */
+#define CMD_OLS_GET_LIMITS		0x6a /* out: u16, u16 */
+#define CMD_OLS_SET_CEILING		0x6b /* in: u16 */
+#define CMD_OLS_GET_CEILING		0x6c /* out: u16 */
+
+/*
+ * Accepted EC commands, and how many bytes they return. There are plenty
+ * of EC commands that are no longer implemented, or are implemented only on
+ * certain older boards.
+ */
+static const struct ec_cmd_t olpc_xo175_ec_cmds[] = {
+	{ CMD_GET_API_VERSION, 1 },
+	{ CMD_READ_VOLTAGE, 2 },
+	{ CMD_READ_CURRENT, 2 },
+	{ CMD_READ_ACR, 2 },
+	{ CMD_READ_BATT_TEMPERATURE, 2 },
+	{ CMD_READ_BATTERY_STATUS, 1 },
+	{ CMD_READ_SOC, 1 },
+	{ CMD_READ_GAUGE_ID, 8 },
+	{ CMD_READ_GAUGE_DATA, 1 },
+	{ CMD_READ_BOARD_ID, 2 },
+	{ CMD_READ_BATT_ERR_CODE, 1 },
+	{ CMD_SET_DCON_POWER, 0 },
+	{ CMD_RESET_EC, 0 },
+	{ CMD_READ_BATTERY_TYPE, 1 },
+	{ CMD_ENABLE_RUNIN_DISCHARGE, 0 },
+	{ CMD_DISABLE_RUNIN_DISCHARGE, 0 },
+	{ CMD_READ_MPPT_ACTIVE, 1 },
+	{ CMD_READ_MPPT_LIMIT, 1 },
+	{ CMD_SET_MPPT_LIMIT, 0 },
+	{ CMD_DISABLE_MPPT, 0 },
+	{ CMD_ENABLE_MPPT, 0 },
+	{ CMD_READ_VIN, 2 },
+	{ CMD_GET_FW_VERSION, 16 },
+	{ CMD_POWER_CYCLE, 0 },
+	{ CMD_POWER_OFF, 0 },
+	{ CMD_RESET_EC_SOFT, 0 },
+	{ CMD_ECHO, 5 },
+	{ CMD_GET_FW_DATE, 16 },
+	{ CMD_GET_FW_USER, 16 },
+	{ CMD_TURN_OFF_POWER, 0 },
+	{ CMD_READ_OLS, 2 },
+	{ CMD_OLS_SMT_LEDON, 0 },
+	{ CMD_OLS_SMT_LEDOFF, 0 },
+	{ CMD_START_OLS_ASSY, 0 },
+	{ CMD_STOP_OLS_ASSY, 0 },
+	{ CMD_OLS_SMTTEST_STOP, 0 },
+	{ CMD_READ_VIN_SCALED, 2 },
+	{ CMD_READ_BAT_MIN_W, 2 },
+	{ CMD_READ_BAR_MAX_W, 2 },
+	{ CMD_RESET_BAT_MINMAX_W, 0 },
+	{ CMD_READ_LOCATION, 1 },
+	{ CMD_WRITE_LOCATION, 0 },
+	{ CMD_GET_FW_HASH, 16 },
+	{ CMD_SUSPEND_HINT, 0 },
+	{ CMD_ENABLE_WAKE_TIMER, 0 },
+	{ CMD_SET_WAKE_TIMER, 0 },
+	{ CMD_ENABLE_WAKE_AUTORESET, 0 },
+	{ CMD_OLS_SET_LIMITS, 0 },
+	{ CMD_OLS_GET_LIMITS, 4 },
+	{ CMD_OLS_SET_CEILING, 0 },
+	{ CMD_OLS_GET_CEILING, 2 },
+	{ CMD_READ_EXT_SCI_MASK, 2 },
+	{ CMD_WRITE_EXT_SCI_MASK, 0 },
+
+	{ }
+};
+
+#define EC_MAX_CMD_DATA_LEN	5
+#define EC_MAX_RESP_LEN		16
+
+#define LOG_BUF_SIZE		128
+
+#define PM_WAKEUP_TIME		1000
+
+#define EC_ALL_EVENTS		GENMASK(15, 0)
+
+enum ec_state_t {
+	CMD_STATE_IDLE = 0,
+	CMD_STATE_WAITING_FOR_SWITCH,
+	CMD_STATE_CMD_IN_TX_FIFO,
+	CMD_STATE_CMD_SENT,
+	CMD_STATE_RESP_RECEIVED,
+	CMD_STATE_ERROR_RECEIVED,
+};
+
+struct olpc_xo175_ec_cmd {
+	u8 command;
+	u8 nr_args;
+	u8 data_len;
+	u8 args[EC_MAX_CMD_DATA_LEN];
+};
+
+struct olpc_xo175_ec_resp {
+	u8 channel;
+	u8 byte;
+};
+
+struct olpc_xo175_ec {
+	bool suspended;
+
+	/* SPI related stuff. */
+	struct spi_device *spi;
+	struct spi_transfer xfer;
+	struct spi_message msg;
+	union {
+		struct olpc_xo175_ec_cmd cmd;
+		struct olpc_xo175_ec_resp resp;
+	} tx_buf, rx_buf;
+
+	/* GPIO for the CMD signals. */
+	struct gpio_desc *gpio_cmd;
+
+	/* Command handling related state. */
+	spinlock_t cmd_state_lock;
+	int cmd_state;
+	bool cmd_running;
+	struct completion cmd_done;
+	struct olpc_xo175_ec_cmd cmd;
+	u8 resp_data[EC_MAX_RESP_LEN];
+	int expected_resp_len;
+	int resp_len;
+
+	/* Power button. */
+	struct input_dev *pwrbtn;
+
+	/* Debug handling. */
+	char logbuf[LOG_BUF_SIZE];
+	int logbuf_len;
+};
+
+static struct platform_device *olpc_ec;
+
+static int olpc_xo175_ec_is_valid_cmd(u8 cmd)
+{
+	const struct ec_cmd_t *p;
+
+	for (p = olpc_xo175_ec_cmds; p->cmd; p++) {
+		if (p->cmd == cmd)
+			return p->bytes_returned;
+	}
+
+	return -EINVAL;
+}
+
+static void olpc_xo175_ec_flush_logbuf(struct olpc_xo175_ec *priv)
+{
+	dev_dbg(&priv->spi->dev, "got debug string [%*pE]\n",
+				priv->logbuf_len, priv->logbuf);
+	priv->logbuf_len = 0;
+}
+
+static void olpc_xo175_ec_complete(void *arg);
+
+static void olpc_xo175_ec_send_command(struct olpc_xo175_ec *priv, void *cmd,
+								size_t cmdlen)
+{
+	int ret;
+
+	memcpy(&priv->tx_buf, cmd, cmdlen);
+	priv->xfer.len = cmdlen;
+
+	spi_message_init_with_transfers(&priv->msg, &priv->xfer, 1);
+
+	priv->msg.complete = olpc_xo175_ec_complete;
+	priv->msg.context = priv;
+
+	ret = spi_async(priv->spi, &priv->msg);
+	if (ret)
+		dev_err(&priv->spi->dev, "spi_async() failed %d\n", ret);
+}
+
+static void olpc_xo175_ec_read_packet(struct olpc_xo175_ec *priv)
+{
+	u8 nonce[] = {0xA5, 0x5A};
+
+	olpc_xo175_ec_send_command(priv, nonce, sizeof(nonce));
+}
+
+static void olpc_xo175_ec_complete(void *arg)
+{
+	struct olpc_xo175_ec *priv = arg;
+	struct device *dev = &priv->spi->dev;
+	struct power_supply *psy;
+	unsigned long flags;
+	u8 channel;
+	u8 byte;
+	int ret;
+
+	ret = priv->msg.status;
+	if (ret) {
+		dev_err(dev, "SPI transfer failed: %d\n", ret);
+
+		spin_lock_irqsave(&priv->cmd_state_lock, flags);
+		if (priv->cmd_running) {
+			priv->resp_len = 0;
+			priv->cmd_state = CMD_STATE_ERROR_RECEIVED;
+			complete(&priv->cmd_done);
+		}
+		spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+
+		if (ret != -EINTR)
+			olpc_xo175_ec_read_packet(priv);
+
+		return;
+	}
+
+	channel = priv->rx_buf.resp.channel;
+	byte = priv->rx_buf.resp.byte;
+
+	switch (channel) {
+	case CHAN_NONE:
+		spin_lock_irqsave(&priv->cmd_state_lock, flags);
+
+		if (!priv->cmd_running) {
+			/* We can safely ignore these */
+			dev_err(dev, "spurious FIFO read packet\n");
+			spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+			return;
+		}
+
+		priv->cmd_state = CMD_STATE_CMD_SENT;
+		if (!priv->expected_resp_len)
+			complete(&priv->cmd_done);
+		olpc_xo175_ec_read_packet(priv);
+
+		spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+		return;
+
+	case CHAN_SWITCH:
+		spin_lock_irqsave(&priv->cmd_state_lock, flags);
+
+		if (!priv->cmd_running) {
+			/* Just go with the flow */
+			dev_err(dev, "spurious SWITCH packet\n");
+			memset(&priv->cmd, 0, sizeof(priv->cmd));
+			priv->cmd.command = CMD_ECHO;
+		}
+
+		priv->cmd_state = CMD_STATE_CMD_IN_TX_FIFO;
+
+		/* Throw command into TxFIFO */
+		gpiod_set_value_cansleep(priv->gpio_cmd, 0);
+		olpc_xo175_ec_send_command(priv, &priv->cmd, sizeof(priv->cmd));
+
+		spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+		return;
+
+	case CHAN_CMD_RESP:
+		spin_lock_irqsave(&priv->cmd_state_lock, flags);
+
+		if (!priv->cmd_running) {
+			dev_err(dev, "spurious response packet\n");
+		} else if (priv->resp_len >= priv->expected_resp_len) {
+			dev_err(dev, "too many response packets\n");
+		} else {
+			priv->resp_data[priv->resp_len++] = byte;
+			if (priv->resp_len == priv->expected_resp_len) {
+				priv->cmd_state = CMD_STATE_RESP_RECEIVED;
+				complete(&priv->cmd_done);
+			}
+		}
+
+		spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+		break;
+
+	case CHAN_CMD_ERROR:
+		spin_lock_irqsave(&priv->cmd_state_lock, flags);
+
+		if (!priv->cmd_running) {
+			dev_err(dev, "spurious cmd error packet\n");
+		} else {
+			priv->resp_data[0] = byte;
+			priv->resp_len = 1;
+			priv->cmd_state = CMD_STATE_ERROR_RECEIVED;
+			complete(&priv->cmd_done);
+		}
+		spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+		break;
+
+	case CHAN_KEYBOARD:
+		dev_warn(dev, "keyboard is not supported\n");
+		break;
+
+	case CHAN_TOUCHPAD:
+		dev_warn(dev, "touchpad is not supported\n");
+		break;
+
+	case CHAN_EVENT:
+		dev_dbg(dev, "got event %.2x\n", byte);
+		switch (byte) {
+		case EVENT_AC_CHANGE:
+			psy = power_supply_get_by_name("olpc-ac");
+			if (psy) {
+				power_supply_changed(psy);
+				power_supply_put(psy);
+			}
+			break;
+		case EVENT_BATTERY_STATUS:
+		case EVENT_BATTERY_CRITICAL:
+		case EVENT_BATTERY_SOC_CHANGE:
+		case EVENT_BATTERY_ERROR:
+			psy = power_supply_get_by_name("olpc-battery");
+			if (psy) {
+				power_supply_changed(psy);
+				power_supply_put(psy);
+			}
+			break;
+		case EVENT_POWER_PRESSED:
+			input_report_key(priv->pwrbtn, KEY_POWER, 1);
+			input_sync(priv->pwrbtn);
+			input_report_key(priv->pwrbtn, KEY_POWER, 0);
+			input_sync(priv->pwrbtn);
+			/* fall through */
+		case EVENT_POWER_PRESS_WAKE:
+		case EVENT_TIMED_HOST_WAKE:
+			pm_wakeup_event(priv->pwrbtn->dev.parent,
+						PM_WAKEUP_TIME);
+			break;
+		default:
+			dev_dbg(dev, "ignored unknown event %.2x\n", byte);
+			break;
+		}
+		break;
+
+	case CHAN_DEBUG:
+		if (byte == '\n') {
+			olpc_xo175_ec_flush_logbuf(priv);
+		} else if (isprint(byte)) {
+			priv->logbuf[priv->logbuf_len++] = byte;
+			if (priv->logbuf_len == LOG_BUF_SIZE)
+				olpc_xo175_ec_flush_logbuf(priv);
+		}
+		break;
+
+	default:
+		dev_warn(dev, "unknown channel: %d, %.2x\n", channel, byte);
+		break;
+	}
+
+	/* Most non-command packets get the TxFIFO refilled and an ACK. */
+	olpc_xo175_ec_read_packet(priv);
+}
+
+/*
+ * This function is protected with a mutex. We can safely assume that
+ * there will be only one instance of this function running at a time.
+ * One of the ways in which we enforce this is by waiting until we get
+ * all response bytes back from the EC, rather than just the number that
+ * the caller requests (otherwise, we might start a new command while an
+ * old command's response bytes are still incoming).
+ */
+static int olpc_xo175_ec_cmd(u8 cmd, u8 *inbuf, size_t inlen, u8 *resp,
+					size_t resp_len, void *ec_cb_arg)
+{
+	struct olpc_xo175_ec *priv = ec_cb_arg;
+	struct device *dev = &priv->spi->dev;
+	unsigned long flags;
+	size_t nr_bytes;
+	int ret = 0;
+
+	dev_dbg(dev, "CMD %x, %d bytes expected\n", cmd, resp_len);
+
+	if (inlen > 5) {
+		dev_err(dev, "command len %d too big!\n", resp_len);
+		return -EOVERFLOW;
+	}
+
+	/* Suspending in the middle of an EC command hoses things badly! */
+	if (WARN_ON(priv->suspended))
+		return -EBUSY;
+
+	/* Ensure a valid command and return bytes */
+	nr_bytes = olpc_xo175_ec_is_valid_cmd(cmd);
+	if (nr_bytes < 0) {
+		dev_err_ratelimited(dev, "unknown command 0x%x\n", cmd);
+
+		/*
+		 * Assume the best in our callers, and allow unknown commands
+		 * through. I'm not the charitable type, but it was beaten
+		 * into me. Just maintain a minimum standard of sanity.
+		 */
+		if (resp_len > sizeof(priv->resp_data)) {
+			dev_err(dev, "response too big: %d!\n", resp_len);
+			return -EOVERFLOW;
+		}
+		nr_bytes = resp_len;
+	}
+	resp_len = min(resp_len, nr_bytes);
+
+	spin_lock_irqsave(&priv->cmd_state_lock, flags);
+
+	/* Initialize the state machine */
+	init_completion(&priv->cmd_done);
+	priv->cmd_running = true;
+	priv->cmd_state = CMD_STATE_WAITING_FOR_SWITCH;
+	memset(&priv->cmd, 0, sizeof(priv->cmd));
+	priv->cmd.command = cmd;
+	priv->cmd.nr_args = inlen;
+	priv->cmd.data_len = 0;
+	memcpy(priv->cmd.args, inbuf, inlen);
+	priv->expected_resp_len = nr_bytes;
+	priv->resp_len = 0;
+
+	/* Tickle the cmd gpio to get things started */
+	gpiod_set_value_cansleep(priv->gpio_cmd, 1);
+
+	spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+
+	/* The irq handler should do the rest */
+	if (!wait_for_completion_timeout(&priv->cmd_done,
+			msecs_to_jiffies(4000))) {
+		dev_err(dev, "EC cmd error: timeout in STATE %d\n",
+				priv->cmd_state);
+		gpiod_set_value_cansleep(priv->gpio_cmd, 0);
+		spi_slave_abort(priv->spi);
+		olpc_xo175_ec_read_packet(priv);
+		return -ETIMEDOUT;
+	}
+
+	spin_lock_irqsave(&priv->cmd_state_lock, flags);
+
+	/* Deal with the results. */
+	if (priv->cmd_state == CMD_STATE_ERROR_RECEIVED) {
+		/* EC-provided error is in the single response byte */
+		dev_err(dev, "command 0x%x returned error 0x%x\n",
+						cmd, priv->resp_data[0]);
+		ret = -EREMOTEIO;
+	} else if (priv->resp_len != nr_bytes) {
+		dev_err(dev, "command 0x%x returned %d bytes, expected %d bytes\n",
+						cmd, priv->resp_len, nr_bytes);
+		ret = -EREMOTEIO;
+	} else {
+		/*
+		 * We may have 8 bytes in priv->resp, but we only care about
+		 * what we've been asked for. If the caller asked for only 2
+		 * bytes, give them that. We've guaranteed that
+		 * resp_len <= priv->resp_len and priv->resp_len == nr_bytes.
+		 */
+		memcpy(resp, priv->resp_data, resp_len);
+	}
+
+	/* This should already be low, but just in case. */
+	gpiod_set_value_cansleep(priv->gpio_cmd, 0);
+	priv->cmd_running = false;
+
+	spin_unlock_irqrestore(&priv->cmd_state_lock, flags);
+
+	return ret;
+}
+
+static int olpc_xo175_ec_set_event_mask(unsigned int mask)
+{
+	unsigned char args[2];
+
+	args[0] = (mask >> 0) & 0xff;
+	args[1] = (mask >> 8) & 0xff;
+	return olpc_ec_cmd(CMD_WRITE_EXT_SCI_MASK, args, 2, NULL, 0);
+}
+
+static void olpc_xo175_ec_restart(enum reboot_mode mode, const char *cmd)
+{
+	while (1) {
+		olpc_ec_cmd(CMD_POWER_CYCLE, NULL, 0, NULL, 0);
+		mdelay(1000);
+	}
+}
+
+static void olpc_xo175_ec_power_off(void)
+{
+	while (1) {
+		olpc_ec_cmd(CMD_POWER_OFF, NULL, 0, NULL, 0);
+		mdelay(1000);
+	}
+}
+
+static int __maybe_unused olpc_xo175_ec_suspend(struct device *dev)
+{
+	struct olpc_xo175_ec *priv = dev_get_drvdata(dev);
+	static struct {
+		u8 suspend;
+		u32 suspend_count;
+	} __packed hintargs;
+	static unsigned int suspend_count;
+
+	/*
+	 * SOC_SLEEP is not wired to the EC on B3 and earlier boards.
+	 * This command lets the EC know instead. The suspend count doesn't seem
+	 * to be used anywhere but in the EC debug output.
+	 */
+	hintargs.suspend = 1;
+	hintargs.suspend_count = suspend_count++;
+	olpc_ec_cmd(CMD_SUSPEND_HINT, (void *)&hintargs, sizeof(hintargs),
+								NULL, 0);
+
+	/*
+	 * After we've sent the suspend hint, don't allow further EC commands
+	 * to be run until we've resumed. Userspace tasks should be frozen,
+	 * but kernel threads and interrupts could still schedule EC commands.
+	 */
+	priv->suspended = true;
+
+	return 0;
+}
+
+static int __maybe_unused olpc_xo175_ec_resume_noirq(struct device *dev)
+{
+	struct olpc_xo175_ec *priv = dev_get_drvdata(dev);
+
+	priv->suspended = false;
+
+	return 0;
+}
+
+static int __maybe_unused olpc_xo175_ec_resume(struct device *dev)
+{
+	u8 x = 0;
+
+	/*
+	 * The resume hint is only needed if no other commands are
+	 * being sent during resume. all it does is tell the EC
+	 * the SoC is definitely awake.
+	 */
+	olpc_ec_cmd(CMD_SUSPEND_HINT, &x, 1, NULL, 0);
+
+	/* Enable all EC events while we're awake */
+	olpc_xo175_ec_set_event_mask(EC_ALL_EVENTS);
+
+	return 0;
+}
+
+static struct olpc_ec_driver olpc_xo175_ec_driver = {
+	.ec_cmd = olpc_xo175_ec_cmd,
+};
+
+static int olpc_xo175_ec_remove(struct spi_device *spi)
+{
+	if (pm_power_off == olpc_xo175_ec_power_off)
+		pm_power_off = NULL;
+	if (arm_pm_restart == olpc_xo175_ec_restart)
+		arm_pm_restart = NULL;
+
+	spi_slave_abort(spi);
+
+	platform_device_unregister(olpc_ec);
+	olpc_ec = NULL;
+
+	return 0;
+}
+
+static int olpc_xo175_ec_probe(struct spi_device *spi)
+{
+	struct olpc_xo175_ec *priv;
+	int ret;
+
+	if (olpc_ec) {
+		dev_err(&spi->dev, "OLPC EC already registered.\n");
+		return -EBUSY;
+	}
+
+	priv = devm_kzalloc(&spi->dev, sizeof(*priv), GFP_KERNEL);
+	if (!priv)
+		return -ENOMEM;
+
+	priv->gpio_cmd = devm_gpiod_get(&spi->dev, "cmd", GPIOD_OUT_LOW);
+	if (IS_ERR(priv->gpio_cmd)) {
+		dev_err(&spi->dev, "failed to get cmd gpio: %ld\n",
+					PTR_ERR(priv->gpio_cmd));
+		return PTR_ERR(priv->gpio_cmd);
+	}
+
+	priv->spi = spi;
+
+	spin_lock_init(&priv->cmd_state_lock);
+	priv->cmd_state = CMD_STATE_IDLE;
+	init_completion(&priv->cmd_done);
+
+	priv->logbuf_len = 0;
+
+	/* Set up power button input device */
+	priv->pwrbtn = devm_input_allocate_device(&spi->dev);
+	if (!priv->pwrbtn)
+		return -ENOMEM;
+	priv->pwrbtn->name = "Power Button";
+	priv->pwrbtn->dev.parent = &spi->dev;
+	input_set_capability(priv->pwrbtn, EV_KEY, KEY_POWER);
+	ret = input_register_device(priv->pwrbtn);
+	if (ret) {
+		dev_err(&spi->dev, "error registering input device: %d\n", ret);
+		return ret;
+	}
+
+	spi_set_drvdata(spi, priv);
+
+	priv->xfer.rx_buf = &priv->rx_buf;
+	priv->xfer.tx_buf = &priv->tx_buf;
+
+	olpc_xo175_ec_read_packet(priv);
+
+	olpc_ec_driver_register(&olpc_xo175_ec_driver, priv);
+	olpc_ec = platform_device_register_resndata(&spi->dev, "olpc-ec", -1,
+							NULL, 0, NULL, 0);
+
+	/* Enable all EC events while we're awake */
+	olpc_xo175_ec_set_event_mask(EC_ALL_EVENTS);
+
+	if (pm_power_off == NULL)
+		pm_power_off = olpc_xo175_ec_power_off;
+	if (arm_pm_restart == NULL)
+		arm_pm_restart = olpc_xo175_ec_restart;
+
+	dev_info(&spi->dev, "OLPC XO-1.75 Embedded Controller driver\n");
+
+	return 0;
+}
+
+static const struct dev_pm_ops olpc_xo175_ec_pm_ops = {
+	SET_NOIRQ_SYSTEM_SLEEP_PM_OPS(NULL, olpc_xo175_ec_resume_noirq)
+	SET_RUNTIME_PM_OPS(olpc_xo175_ec_suspend, olpc_xo175_ec_resume, NULL)
+};
+
+static const struct of_device_id olpc_xo175_ec_of_match[] = {
+	{ .compatible = "olpc,xo1.75-ec" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, olpc_xo175_ec_of_match);
+
+static struct spi_driver olpc_xo175_ec_spi_driver = {
+	.driver = {
+		.name	= "olpc-xo175-ec",
+		.of_match_table = olpc_xo175_ec_of_match,
+		.pm = &olpc_xo175_ec_pm_ops,
+	},
+	.probe		= olpc_xo175_ec_probe,
+	.remove		= olpc_xo175_ec_remove,
+};
+module_spi_driver(olpc_xo175_ec_spi_driver);
+
+MODULE_DESCRIPTION("OLPC XO-1.75 Embedded Controller driver");
+MODULE_AUTHOR("Lennert Buytenhek <buytenh@wantstofly.org>"); /* Functionality */
+MODULE_AUTHOR("Lubomir Rintel <lkundrak@v3.sk>"); /* Bugs */
+MODULE_LICENSE("GPL");