From: Hans de Goede <hdegoede@redhat.com>
To: "Rafael J . Wysocki" <rjw@rjwysocki.net>,
Len Brown <lenb@kernel.org>, Darren Hart <dvhart@infradead.org>,
Andy Shevchenko <andy@infradead.org>,
Jonathan Cameron <jic23@kernel.org>
Cc: Hans de Goede <hdegoede@redhat.com>,
linux-acpi@vger.kernel.org, platform-driver-x86@vger.kernel.org,
linux-kernel@vger.kernel.org, Hartmut Knaack <knaack.h@gmx.de>,
Lars-Peter Clausen <lars@metafoo.de>,
Peter Meerwald-Stadler <pmeerw@pmeerw.net>,
linux-iio@vger.kernel.org,
Andy Shevchenko <andy.shevchenko@gmail.com>
Subject: [PATCH v4 08/11] iio: light: cm32181: Use units of 1/100000th for calibscale and lux_per_bit
Date: Mon, 4 May 2020 14:55:48 +0200 [thread overview]
Message-ID: <20200504125551.434647-8-hdegoede@redhat.com> (raw)
In-Reply-To: <20200504125551.434647-1-hdegoede@redhat.com>
Use units of 1/100000th for calibscale and lux_per_bit. The similar
cm3232 driver already uses 1/100000th as unit for calibscale.
This allows for higher-accuracy and makes it easier to add support
for getting device-specific calibscale and lux_per_bit values from
a device's ACPI tables, as the values in the ACPI tables also use
1/100000th units.
This units change means that our intermediate values in cm32181_get_lux()
may get quite big, change the type of the lux variable to a u64 to
deal with this.
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
---
drivers/iio/light/cm32181.c | 22 +++++++++++-----------
1 file changed, 11 insertions(+), 11 deletions(-)
diff --git a/drivers/iio/light/cm32181.c b/drivers/iio/light/cm32181.c
index f5af986e1ed4..59c95e22ad00 100644
--- a/drivers/iio/light/cm32181.c
+++ b/drivers/iio/light/cm32181.c
@@ -45,11 +45,11 @@
#define CM32181_CMD_ALS_SM_MASK (0x03 << CM32181_CMD_ALS_SM_SHIFT)
#define CM32181_CMD_ALS_SM_DEFAULT (0x01 << CM32181_CMD_ALS_SM_SHIFT)
-#define CM32181_MLUX_PER_BIT 5 /* ALS_SM=01 IT=800ms */
-#define CM32181_MLUX_PER_BIT_BASE_IT 800000 /* Based on IT=800ms */
-#define CM32181_CALIBSCALE_DEFAULT 1000
-#define CM32181_CALIBSCALE_RESOLUTION 1000
-#define MLUX_PER_LUX 1000
+#define CM32181_LUX_PER_BIT 500 /* ALS_SM=01 IT=800ms */
+#define CM32181_LUX_PER_BIT_RESOLUTION 100000
+#define CM32181_LUX_PER_BIT_BASE_IT 800000 /* Based on IT=800ms */
+#define CM32181_CALIBSCALE_DEFAULT 100000
+#define CM32181_CALIBSCALE_RESOLUTION 100000
#define SMBUS_ALERT_RESPONSE_ADDRESS 0x0c
@@ -219,15 +219,15 @@ static int cm32181_get_lux(struct cm32181_chip *cm32181)
struct i2c_client *client = cm32181->client;
int ret;
int als_it;
- unsigned long lux;
+ u64 lux;
ret = cm32181_read_als_it(cm32181, &als_it);
if (ret < 0)
return -EINVAL;
- lux = CM32181_MLUX_PER_BIT;
- lux *= CM32181_MLUX_PER_BIT_BASE_IT;
- lux /= als_it;
+ lux = CM32181_LUX_PER_BIT;
+ lux *= CM32181_LUX_PER_BIT_BASE_IT;
+ lux = div_u64(lux, als_it);
ret = i2c_smbus_read_word_data(client, CM32181_REG_ADDR_ALS);
if (ret < 0)
@@ -235,8 +235,8 @@ static int cm32181_get_lux(struct cm32181_chip *cm32181)
lux *= ret;
lux *= cm32181->calibscale;
- lux /= CM32181_CALIBSCALE_RESOLUTION;
- lux /= MLUX_PER_LUX;
+ lux = div_u64(lux, CM32181_CALIBSCALE_RESOLUTION);
+ lux = div_u64(lux, CM32181_LUX_PER_BIT_RESOLUTION);
if (lux > 0xFFFF)
lux = 0xFFFF;
--
2.26.0
next prev parent reply other threads:[~2020-05-04 12:56 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-05-04 12:55 [PATCH v4 01/11] iio: light: cm32181: Switch to new style i2c-driver probe function Hans de Goede
2020-05-04 12:55 ` [PATCH v4 02/11] iio: light: cm32181: Add support for ACPI enumeration Hans de Goede
2020-05-04 12:55 ` [PATCH v4 03/11] iio: light: cm32181: Add some extra register defines Hans de Goede
2020-05-04 12:55 ` [PATCH v4 04/11] iio: light: cm32181: Add support for the CM3218 Hans de Goede
2020-05-04 12:55 ` [PATCH v4 05/11] iio: light: cm32181: Clean up the probe function a bit Hans de Goede
2020-05-04 12:55 ` [PATCH v4 06/11] iio: light: cm32181: Handle CM3218 ACPI devices with 2 I2C resources Hans de Goede
2020-05-04 12:55 ` [PATCH v4 07/11] iio: light: cm32181: Change reg_init to use a bitmap of which registers to init Hans de Goede
2020-05-04 12:55 ` Hans de Goede [this message]
2020-05-04 12:55 ` [PATCH v4 09/11] iio: light: cm32181: Make lux_per_bit and lux_per_bit_base_it runtime settings Hans de Goede
2020-05-04 12:55 ` [PATCH v4 10/11] iio: light: cm32181: Add support for parsing CPM0 and CPM1 ACPI tables Hans de Goede
2020-05-11 19:20 ` Jonathan Cameron
2020-05-12 8:26 ` Hans de Goede
2020-05-04 12:55 ` [PATCH v4 11/11] iio: light: cm32181: Fix integartion time typo Hans de Goede
2020-05-10 9:48 ` [PATCH v4 01/11] iio: light: cm32181: Switch to new style i2c-driver probe function Jonathan Cameron
2020-05-10 10:03 ` Hans de Goede
2020-05-10 11:00 ` Jonathan Cameron
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