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    SubjectRe: [PATCH v2 16/16] hwmon: (mr75203) add debugfs to read and write temperature coefficients
    On Wed, Aug 17, 2022 at 05:43:21AM +0000, Eliav Farber wrote:
    > This change adds debugfs to read and write TS coefficients - g, h, j and
    > cal5.
    >
    > The coefficients can vary between product and product, so to calibrate
    > them it can be very useful to to be able to modify them on the fly.
    >
    > e.g.
    >
    > cat /sys/kernel/debug/940f23d0000.pvt/ts_coeff_cal5
    > 4096
    >
    > echo 83000 > sys/kernel/debug/940f23d0000.pvt/ts_coeff_g
    >

    What happens if you write 0 into all those attributes, or 0xffffffff ?

    Guenter

    > Signed-off-by: Eliav Farber <farbere@amazon.com>
    > ---
    > drivers/hwmon/mr75203.c | 196 ++++++++++++++++++++++++++++++++++++++++
    > 1 file changed, 196 insertions(+)
    >
    > diff --git a/drivers/hwmon/mr75203.c b/drivers/hwmon/mr75203.c
    > index 2898565afaab..ce34a44237e8 100644
    > --- a/drivers/hwmon/mr75203.c
    > +++ b/drivers/hwmon/mr75203.c
    > @@ -9,6 +9,7 @@
    > */
    > #include <linux/bits.h>
    > #include <linux/clk.h>
    > +#include <linux/debugfs.h>
    > #include <linux/hwmon.h>
    > #include <linux/module.h>
    > #include <linux/mod_devicetable.h>
    > @@ -127,6 +128,7 @@ struct pvt_device {
    > struct clk *clk;
    > struct reset_control *rst;
    > struct voltage_device *vd;
    > + struct dentry *dbgfs_dir;
    > u32 t_num;
    > u32 p_num;
    > u32 v_num;
    > @@ -139,6 +141,198 @@ struct pvt_device {
    > u8 vm_ch_total;
    > };
    >
    > +static ssize_t pvt_ts_coeff_h_read(struct file *file,
    > + char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + char buf[16];
    > + unsigned int len;
    > +
    > + len = sprintf(buf, "%u\n", pvt->ts_coeff_h);
    > +
    > + return simple_read_from_buffer(user_buf, count, ppos, buf, len);
    > +}
    > +
    > +static ssize_t pvt_ts_coeff_h_write(struct file *file,
    > + const char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + int ret;
    > + u32 coeff;
    > +
    > + ret = kstrtou32_from_user(user_buf, count, 0, &coeff);
    > + if (ret)
    > + return ret;
    > +
    > + pvt->ts_coeff_h = coeff;
    > +
    > + return count;
    > +}
    > +
    > +static const struct file_operations pvt_ts_coeff_h_fops = {
    > + .read = pvt_ts_coeff_h_read,
    > + .write = pvt_ts_coeff_h_write,
    > + .open = simple_open,
    > + .owner = THIS_MODULE,
    > + .llseek = default_llseek,
    > +};
    > +
    > +static ssize_t pvt_ts_coeff_g_read(struct file *file,
    > + char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + char buf[16];
    > + unsigned int len;
    > +
    > + len = sprintf(buf, "%u\n", pvt->ts_coeff_g);
    > +
    > + return simple_read_from_buffer(user_buf, count, ppos, buf, len);
    > +}
    > +
    > +static ssize_t pvt_ts_coeff_g_write(struct file *file,
    > + const char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + int ret;
    > + u32 coeff;
    > +
    > + ret = kstrtou32_from_user(user_buf, count, 0, &coeff);
    > + if (ret)
    > + return ret;
    > +
    > + pvt->ts_coeff_g = coeff;
    > +
    > + return count;
    > +}
    > +
    > +static const struct file_operations pvt_ts_coeff_g_fops = {
    > + .read = pvt_ts_coeff_g_read,
    > + .write = pvt_ts_coeff_g_write,
    > + .open = simple_open,
    > + .owner = THIS_MODULE,
    > + .llseek = default_llseek,
    > +};
    > +
    > +static ssize_t pvt_ts_coeff_j_read(struct file *file,
    > + char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + char buf[16];
    > + unsigned int len;
    > +
    > + len = sprintf(buf, "%d\n", pvt->ts_coeff_j);
    > +
    > + return simple_read_from_buffer(user_buf, count, ppos, buf, len);
    > +}
    > +
    > +static ssize_t pvt_ts_coeff_j_write(struct file *file,
    > + const char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + int ret;
    > + s32 coeff;
    > +
    > + ret = kstrtos32_from_user(user_buf, count, 0, &coeff);
    > + if (ret)
    > + return ret;
    > +
    > + pvt->ts_coeff_j = coeff;
    > +
    > + return count;
    > +}
    > +
    > +static const struct file_operations pvt_ts_coeff_j_fops = {
    > + .read = pvt_ts_coeff_j_read,
    > + .write = pvt_ts_coeff_j_write,
    > + .open = simple_open,
    > + .owner = THIS_MODULE,
    > + .llseek = default_llseek,
    > +};
    > +
    > +static ssize_t pvt_ts_coeff_cal5_read(struct file *file,
    > + char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + char buf[16];
    > + unsigned int len;
    > +
    > + len = sprintf(buf, "%u\n", pvt->ts_coeff_cal5);
    > +
    > + return simple_read_from_buffer(user_buf, count, ppos, buf, len);
    > +}
    > +
    > +static ssize_t pvt_ts_coeff_cal5_write(struct file *file,
    > + const char __user *user_buf,
    > + size_t count, loff_t *ppos)
    > +{
    > + struct pvt_device *pvt = file->private_data;
    > + int ret;
    > + u32 coeff;
    > +
    > + ret = kstrtou32_from_user(user_buf, count, 0, &coeff);
    > + if (ret)
    > + return ret;
    > +
    > + if (coeff == 0)
    > + return -EINVAL;
    > +
    > + pvt->ts_coeff_cal5 = coeff;
    > +
    > + return count;
    > +}
    > +
    > +static const struct file_operations pvt_ts_coeff_cal5_fops = {
    > + .read = pvt_ts_coeff_cal5_read,
    > + .write = pvt_ts_coeff_cal5_write,
    > + .open = simple_open,
    > + .owner = THIS_MODULE,
    > + .llseek = default_llseek,
    > +};
    > +
    > +static void devm_pvt_ts_dbgfs_remove(void *data)
    > +{
    > + struct pvt_device *pvt = (struct pvt_device *)data;
    > +
    > + debugfs_remove_recursive(pvt->dbgfs_dir);
    > + pvt->dbgfs_dir = NULL;
    > +}
    > +
    > +static int pvt_ts_dbgfs_create(struct pvt_device *pvt, struct device *dev)
    > +{
    > + int ret;
    > +
    > + pvt->dbgfs_dir = debugfs_create_dir(dev_name(dev), NULL);
    > + if (!pvt->dbgfs_dir) {
    > + dev_err(dev, "Failed to create dbgfs_dir\n");
    > + return -EINVAL;
    > + }
    > +
    > + debugfs_create_file("ts_coeff_h", 0644, pvt->dbgfs_dir, pvt,
    > + &pvt_ts_coeff_h_fops);
    > + debugfs_create_file("ts_coeff_g", 0644, pvt->dbgfs_dir, pvt,
    > + &pvt_ts_coeff_g_fops);
    > + debugfs_create_file("ts_coeff_j", 0644, pvt->dbgfs_dir, pvt,
    > + &pvt_ts_coeff_j_fops);
    > + debugfs_create_file("ts_coeff_cal5", 0644, pvt->dbgfs_dir, pvt,
    > + &pvt_ts_coeff_cal5_fops);
    > +
    > + ret = devm_add_action_or_reset(dev, devm_pvt_ts_dbgfs_remove, pvt);
    > + if (ret) {
    > + dev_err(dev, "failed to add action to remove pvt dbgfs (%d)\n",
    > + ret);
    > + return ret;
    > + }
    > +
    > + return 0;
    > +}
    > +
    > static umode_t pvt_is_visible(const void *data, enum hwmon_sensor_types type,
    > u32 attr, int channel)
    > {
    > @@ -655,6 +849,8 @@ static int mr75203_probe(struct platform_device *pdev)
    > dev_dbg(dev, "ts-coeff: h = %u, g = %u, j = %d, cal5 = %u\n",
    > pvt->ts_coeff_h, pvt->ts_coeff_g, pvt->ts_coeff_j,
    > pvt->ts_coeff_cal5);
    > +
    > + pvt_ts_dbgfs_create(pvt, dev);
    > }
    >
    > if (pd_num) {

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