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    SubjectRe: [PATCH 06/15] Platform: OLPC: Add XO-1.75 EC driver
    On Wed, Oct 10, 2018 at 8:24 PM Lubomir Rintel <lkundrak@v3.sk> 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.


    > +#include <asm/system_misc.h>

    asm/* goes after linux/*

    > +#include <linux/delay.h>
    > +#include <linux/gpio/consumer.h>
    > +#include <linux/spinlock.h>
    > +#include <linux/completion.h>
    > +#include <linux/slab.h>
    > +#include <linux/platform_device.h>
    > +#include <linux/ctype.h>
    > +#include <linux/olpc-ec.h>
    > +#include <linux/spi/spi.h>
    > +#include <linux/reboot.h>
    > +#include <linux/input.h>
    > +#include <linux/kfifo.h>
    > +#include <linux/module.h>
    > +#include <linux/power_supply.h>

    Easy to maintain when it's sorted.

    > + { 0 },

    Terminators are better without trailing comma.

    > +#define EC_CMD_LEN 8
    > +#define EC_MAX_RESP_LEN 16

    > +#define LOG_BUF_SIZE 127

    127 sounds slightly strange. Is it by specification of protocol? Would
    it be better to define it 128 bytes / items?

    > +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 -1;

    -EINVAL ?

    > +}

    > +static void olpc_xo175_ec_complete(void *arg);

    Hmm... Can we avoid forward declaration?

    > + channel = priv->rx_buf[0];
    > + byte = priv->rx_buf[1];

    Maybe specific structures would fit better?

    Like

    struct olpc_ec_resp_hdr {
    u8 channel;
    u8 byte;
    ...
    }

    > + dev_warn(dev, "kbd/tpad not supported\n");

    Please, spell it fully as touchpad and keyboard.

    > + pm_wakeup_event(priv->pwrbtn->dev.parent, 1000);

    Magic number.

    > + /* For now, we just ignore the unknown events. */

    dev_dbg(dev, "Ignored unknown event %.2x\n", byte);

    ?

    > if (isprint(byte)) {
    > + priv->logbuf[priv->logbuf_len++] = byte;
    > + if (priv->logbuf_len == LOG_BUF_SIZE)
    > + olpc_xo175_ec_flush_logbuf(priv);
    > + }

    You may consider to take everything and run %pE when printing instead of %s.

    > +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;
    > + int nr_bytes;
    > + int ret = 0;
    > +
    > + dev_dbg(dev, "CMD %x, %d bytes expected\n", cmd, resp_len);
    > +
    > + if (inlen > 5) {

    Magic number.

    > + dev_err(dev, "command len %d too big!\n", resp_len);
    > + return -EOVERFLOW;
    > + }

    > + WARN_ON(priv->suspended);
    > + if (priv->suspended)

    if (WARN_ON(...)) ?

    > + return -EBUSY;

    > + if (resp_len > nr_bytes)
    > + resp_len = nr_bytes;

    resp_len = min(resp_len, nr_bytes);

    > + priv->cmd[0] = cmd;
    > + priv->cmd[1] = inlen;
    > + priv->cmd[2] = 0;

    Perhaps specific struct header for this?

    > + memset(resp, 0, resp_len);

    Wouldn't be better to do this in where actual response has been filled?

    > + if (!wait_for_completion_timeout(&priv->cmd_done,
    > + msecs_to_jiffies(4000))) {

    Magic number.

    > + }

    > + /* Deal with the results. */

    Somehow feels noisy / unneeded comment.

    > + 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[0]);

    Indentation.

    > + 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 = -ETIMEDOUT;

    In the message I see nothing about timeout.

    > + } else {

    > + }

    > +}


    > +static int olpc_xo175_ec_set_event_mask(unsigned int mask)
    > +{
    > + unsigned char args[2];

    u8

    > +
    > + args[0] = mask & 0xff;
    > + args[1] = (mask >> 8) & 0xff;

    ...mask >> 0;
    ...mask >> 8;

    > + 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);
    > + }
    > +}
    > +

    > +#ifdef CONFIG_PM
    > +static int olpc_xo175_ec_suspend(struct device *dev)

    __maybe_unused instead of ugly #ifdef?

    > +{

    > + struct platform_device *pdev = to_platform_device(dev);
    > + struct olpc_xo175_ec *priv = platform_get_drvdata(pdev);

    dev_get_drvdata() or how is it called?

    > + unsigned char hintargs[5];

    struct olpc_ec_hint_cmd {
    u8 ...
    u32 ...
    };

    ?

    > + static unsigned int suspend_count;

    u32 I suppose.

    > +
    > + suspend_count++;
    > + dev_dbg(dev, "%s: suspend sync %08x\n", __func__, suspend_count);

    __func__ can be issued if user asked for via Dynamic Debug interface.

    > + /*
    > + * First byte is 1 to indicate suspend, the rest is an integer
    > + * counter.
    > + */
    > + hintargs[0] = 1;
    > + memcpy(&hintargs[1], &suspend_count, 4);
    > + olpc_ec_cmd(CMD_SUSPEND_HINT, hintargs, 5, NULL, 0);

    What do you need this counter for?

    > + priv->suspended = true;

    Hmm... Who is the user of it?

    > + return 0;
    > +}
    > +
    > +static int olpc_xo175_ec_resume_noirq(struct device *dev)
    > +{
    > + struct platform_device *pdev = to_platform_device(dev);
    > + struct olpc_xo175_ec *priv = platform_get_drvdata(pdev);
    > +
    > + priv->suspended = false;
    > +
    > + return 0;
    > +}
    > +
    > +static int olpc_xo175_ec_resume(struct device *dev)
    > +{
    > + struct platform_device *pdev = to_platform_device(dev);
    > + struct olpc_xo175_ec *priv = platform_get_drvdata(pdev);

    > + unsigned char x = 0;

    u8

    > + priv->suspended = false;

    Isn't it redundant since noirq callback above?

    > + /*
    > + * 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(0xffff);

    #define EC_ALL_EVENTS GENMASK(15, 0)

    > +}
    > +#endif

    > +static struct platform_device *olpc_ec;

    I would rather see this at the top of file.

    > +static int olpc_xo175_ec_probe(struct spi_device *spi)
    > +{

    > + if (olpc_ec) {
    > + dev_err(&spi->dev, "OLPC EC already registered.\n");
    > + return -EBUSY;
    > + }

    It's racy against parallel probe called. I don't think it would be a
    real issue, just let you know.


    > + /* 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;
    > + }

    I would split out power button driver, but it's up to you.


    > + /* Enable all EC events while we're awake */
    > + olpc_xo175_ec_set_event_mask(0xffff);

    See above about this magic.

    > +}

    > +#ifdef CONFIG_PM
    > + .suspend = olpc_xo175_ec_suspend,
    > + .resume_noirq = olpc_xo175_ec_resume_noirq,
    > + .resume = olpc_xo175_ec_resume,
    > +#endif

    SET_SYSTEM_SLEEP_PM_OPS() ?
    SET_NOIRQ_SYSTEM_SLEEP_PM_OPS() ?

    > +static const struct of_device_id olpc_xo175_ec_of_match[] = {
    > + { .compatible = "olpc,xo1.75-ec" },

    > + { },

    No comma for terminators.

    > +};

    --
    With Best Regards,
    Andy Shevchenko

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