Messages in this thread | | | Date | Thu, 27 Jan 2022 10:41:16 +0100 | From | Greg KH <> | Subject | Re: [PATCH 2/2] drivers/misc: add transfer ioctl for HPS |
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On Thu, Jan 27, 2022 at 07:35:45PM +1100, Sami Kyöstilä wrote: > This patch adds an ioctl operation for sending and receiving data from > the ChromeOS snooping protection sensor (a.k.a., HPS). This allows > userspace programs to perform a combined read/write I2C transaction > through a single syscall. > > The I2C wire protocol for the device is documented at: > > https://chromium.googlesource.com/chromiumos/platform/hps-firmware/+/ > refs/heads/main/docs/host_device_i2c_protocol.md > > Signed-off-by: Sami Kyöstilä <skyostil@chromium.org> > --- > > MAINTAINERS | 1 + > drivers/misc/hps-i2c.c | 81 ++++++++++++++++++++++++++++++++++++++++ > include/uapi/linux/hps.h | 20 ++++++++++ > 3 files changed, 102 insertions(+) > create mode 100644 include/uapi/linux/hps.h > > diff --git a/MAINTAINERS b/MAINTAINERS > index 9dea4b8c2ab5..d5fc066fdbc2 100644 > --- a/MAINTAINERS > +++ b/MAINTAINERS > @@ -8803,6 +8803,7 @@ M: Sami Kyöstilä <skyostil@chromium.org> > R: Evan Benn <evanbenn@chromium.org> > S: Maintained > F: drivers/misc/hps-i2c.c > +F: include/uapi/linux/hps.h > > HSI SUBSYSTEM > M: Sebastian Reichel <sre@kernel.org> > diff --git a/drivers/misc/hps-i2c.c b/drivers/misc/hps-i2c.c > index fe9f073b0352..748ead49d678 100644 > --- a/drivers/misc/hps-i2c.c > +++ b/drivers/misc/hps-i2c.c > @@ -17,9 +17,11 @@ > #include <linux/i2c.h> > #include <linux/module.h> > #include <linux/pm_runtime.h> > +#include <uapi/linux/hps.h> > > #define HPS_ACPI_ID "GOOG0020" > #define HPS_MAX_DEVICES 1 > +#define HPS_MAX_MSG_SIZE 8192 > > struct hps_drvdata { > struct i2c_client *client; > @@ -60,6 +62,8 @@ static int hps_open(struct inode *inode, struct file *file) > ret = pm_runtime_get_sync(dev); > if (ret < 0) > goto pm_get_fail; > + > + file->private_data = hps->client; > return 0; > > pm_get_fail: > @@ -84,10 +88,87 @@ static int hps_release(struct inode *inode, struct file *file) > return ret; > } > > +static int hps_do_ioctl_transfer(struct i2c_client *client, > + struct hps_transfer_ioctl_data *args) > +{ > + int ret; > + int nmsg = 0; > + struct i2c_msg msgs[2] = { > + { > + .addr = client->addr, > + .flags = client->flags, > + }, > + { > + .addr = client->addr, > + .flags = client->flags, > + }, > + }; > + > + if (args->isize) { > + msgs[nmsg].len = args->isize; > + msgs[nmsg].buf = memdup_user(args->ibuf, args->isize); > + if (IS_ERR(msgs[nmsg].buf)) { > + ret = PTR_ERR(msgs[nmsg].buf); > + goto memdup_fail; > + } > + nmsg++; > + } > + > + if (args->osize) { > + msgs[nmsg].len = args->osize; > + msgs[nmsg].buf = memdup_user(args->obuf, args->osize); > + msgs[nmsg].flags |= I2C_M_RD; > + if (IS_ERR(msgs[nmsg].buf)) { > + ret = PTR_ERR(msgs[nmsg].buf); > + goto memdup_fail; > + } > + nmsg++; > + } > + > + ret = i2c_transfer(client->adapter, &msgs[0], nmsg); > + if (ret > 0 && args->osize) { > + if (copy_to_user(args->obuf, msgs[nmsg - 1].buf, ret)) > + ret = -EFAULT; > + }
Why can't you just do normal i2c transfers to/from userspace instead of requring a custom ioctl?
thanks,
greg k-h
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