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Message-ID: <b0f136eb616876018f2a952ee60d7376258e66fd.camel@gmail.com>
Date: Mon, 07 Apr 2025 17:21:43 +0100
From: Nuno Sá <noname.nuno@...il.com>
To: Angelo Dureghello <adureghello@...libre.com>, Nuno Sá
<nuno.sa@...log.com>, Jonathan Cameron <jic23@...nel.org>, Lars-Peter
Clausen <lars@...afoo.de>, Jonathan Corbet <corbet@....net>, Olivier
Moysan <olivier.moysan@...s.st.com>, Michael Hennerich
<Michael.Hennerich@...log.com>
Cc: linux-iio@...r.kernel.org, linux-doc@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH v3 5/5] iio: dac: ad3552r-hs: add support for internal
ramp
On Mon, 2025-04-07 at 10:52 +0200, Angelo Dureghello wrote:
> From: Angelo Dureghello <adureghello@...libre.com>
>
> The ad3552r can be feeded from the HDL controller by an internally
> generated 16bit ramp, useful for debug pourposes. Add debugfs a file
> to enable or disable it.
>
> Signed-off-by: Angelo Dureghello <adureghello@...libre.com>
> ---
> drivers/iio/dac/ad3552r-hs.c | 124 ++++++++++++++++++++++++++++++++++++++++--
> -
> 1 file changed, 118 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/iio/dac/ad3552r-hs.c b/drivers/iio/dac/ad3552r-hs.c
> index
> 37397e188f225a8099745ec03f7c604da76960b1..3dcbda23c732f5f5e655bde31c5dab496055
> 4bfc 100644
> --- a/drivers/iio/dac/ad3552r-hs.c
> +++ b/drivers/iio/dac/ad3552r-hs.c
> @@ -7,6 +7,7 @@
> */
>
> #include <linux/bitfield.h>
> +#include <linux/debugfs.h>
> #include <linux/delay.h>
> #include <linux/gpio/consumer.h>
> #include <linux/iio/backend.h>
> @@ -54,8 +55,13 @@ struct ad3552r_hs_state {
> struct ad3552r_hs_platform_data *data;
> /* INTERFACE_CONFIG_D register cache, in DDR we cannot read values.
> */
> u32 config_d;
> + /* Protects backend I/O operations from concurrent accesses. */
> + struct mutex lock;
> };
>
> +static const char dbgfs_src_iio_buffer[] = "iio-buffer";
> +static const char dbgfs_src_backend_ramp_gen[] = "backend-ramp-generator";
> +
Why not having both strings in one array? See below...
> static int ad3552r_hs_reg_read(struct ad3552r_hs_state *st, u32 reg, u32
> *val,
> size_t xfer_size)
> {
> @@ -65,6 +71,18 @@ static int ad3552r_hs_reg_read(struct ad3552r_hs_state *st,
> u32 reg, u32 *val,
> return st->data->bus_reg_read(st->back, reg, val, xfer_size);
> }
>
> +static int ad3552r_hs_set_data_source(struct ad3552r_hs_state *st,
> + enum iio_backend_data_source type)
> +{
> + int ret;
> +
> + ret = iio_backend_data_source_set(st->back, 0, type);
> + if (ret)
> + return ret;
> +
> + return iio_backend_data_source_set(st->back, 1, type);
Do we have some number of channels variable in some chip info? If so, I would
loop over that. If not, disregard the comment...
> +}
> +
> static int ad3552r_hs_update_reg_bits(struct ad3552r_hs_state *st, u32 reg,
> u32 mask, u32 val, size_t xfer_size)
> {
> @@ -483,6 +501,76 @@ static int ad3552r_hs_reg_access(struct iio_dev
> *indio_dev, unsigned int reg,
> return st->data->bus_reg_write(st->back, reg, writeval, 1);
> }
>
> +static ssize_t ad3552r_hs_show_data_source(struct file *f, char __user
> *userbuf,
> + size_t count, loff_t *ppos)
> +{
> + struct ad3552r_hs_state *st = file_inode(f)->i_private;
> + enum iio_backend_data_source type;
> + int ret;
> +
> + guard(mutex)(&st->lock);
> +
> + ret = iio_backend_data_source_get(st->back, 0, &type);
> + if (ret)
> + return ret;
> +
> + switch (type) {
> + case IIO_BACKEND_INTERNAL_RAMP_16BIT:
> + return simple_read_from_buffer(userbuf, count, ppos,
> + dbgfs_src_backend_ramp_gen,
> + strlen(dbgfs_src_backend_ramp_gen));
> + case IIO_BACKEND_EXTERNAL:
> + return simple_read_from_buffer(userbuf, count, ppos,
> + dbgfs_src_iio_buffer, strlen(dbgfs_src_iio_buffer));
Even with only one array, you could easily handle things here...
> + default:
> + return -EINVAL;
> + }
> +}
> +
> +static ssize_t ad3552r_hs_write_data_source(struct file *f,
> + const char __user *userbuf,
> + size_t count, loff_t *ppos)
> +{
> + struct ad3552r_hs_state *st = file_inode(f)->i_private;
> + char buf[64];
> + int ret, len;
> +
> + guard(mutex)(&st->lock);
> +
> + ret = simple_write_to_buffer(buf, sizeof(buf) - 1, ppos, userbuf,
> + count);
> + if (ret < 0)
> + return ret;
> +
> + len = strlen(dbgfs_src_iio_buffer);
> + if (count == len && !strncmp(buf, dbgfs_src_iio_buffer, len)) {
> + ret = ad3552r_hs_set_data_source(st, IIO_BACKEND_EXTERNAL);
> + if (ret)
> + return ret;
> + goto exit_ok;
> + }
> +
> + len = strlen(dbgfs_src_backend_ramp_gen);
> + if (count == len && !strncmp(buf, dbgfs_src_backend_ramp_gen, len)) {
> + ret = ad3552r_hs_set_data_source(st,
> + IIO_BACKEND_INTERNAL_RAMP_16BIT);
> + if (ret)
> + return ret;
> + goto exit_ok;
> + }
But here is where it makes more sense... I would use match_string() and then get
the match index and translate that into the backend signal type.
Plus, I still think you could provide a 'data_source_available' attribute to
make the user interface more friendly.
- Nuno Sá
> +
> + return -EINVAL;
> +
> +exit_ok:
> + return count;
> +}
> +
> +static const struct file_operations ad3552r_hs_data_source_fops = {
> + .owner = THIS_MODULE,
> + .write = ad3552r_hs_write_data_source,
> + .read = ad3552r_hs_show_data_source,
> +};
> +
> static int ad3552r_hs_setup(struct ad3552r_hs_state *st)
> {
> u16 id;
> @@ -550,11 +638,7 @@ static int ad3552r_hs_setup(struct ad3552r_hs_state *st)
> if (ret)
> return ret;
>
> - ret = iio_backend_data_source_set(st->back, 0, IIO_BACKEND_EXTERNAL);
> - if (ret)
> - return ret;
> -
> - ret = iio_backend_data_source_set(st->back, 1, IIO_BACKEND_EXTERNAL);
> + ret = ad3552r_hs_set_data_source(st, IIO_BACKEND_EXTERNAL);
> if (ret)
> return ret;
>
> @@ -661,6 +745,24 @@ static const struct iio_info ad3552r_hs_info = {
> .debugfs_reg_access = &ad3552r_hs_reg_access,
> };
>
> +static void ad3552r_hs_debugfs_init(struct iio_dev *indio_dev)
> +{
> + struct ad3552r_hs_state *st = iio_priv(indio_dev);
> + struct dentry *d = iio_get_debugfs_dentry(indio_dev);
> +
> + if (!IS_ENABLED(CONFIG_DEBUG_FS))
> + return;
> +
> + d = iio_get_debugfs_dentry(indio_dev);
> + if (!d) {
> + dev_warn(st->dev, "can't set debugfs in driver dir\n");
> + return;
> + }
> +
> + debugfs_create_file("data_source", 0600, d, st,
> + &ad3552r_hs_data_source_fops);
> +}
> +
> static int ad3552r_hs_probe(struct platform_device *pdev)
> {
> struct ad3552r_hs_state *st;
> @@ -705,7 +807,17 @@ static int ad3552r_hs_probe(struct platform_device *pdev)
> if (ret)
> return ret;
>
> - return devm_iio_device_register(&pdev->dev, indio_dev);
> + ret = devm_iio_device_register(&pdev->dev, indio_dev);
> + if (ret)
> + return ret;
> +
> + ret = devm_mutex_init(&pdev->dev, &st->lock);
> + if (ret)
> + return ret;
> +
> + ad3552r_hs_debugfs_init(indio_dev);
> +
> + return ret;
> }
>
> static const struct of_device_id ad3552r_hs_of_id[] = {
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