[PATCH resend v1 1/3] units: Add SI metric prefix definitions

[PATCH resend v1 1/3] units: Add SI metric prefix definitions

[Andy Shevchenko]

Sometimes it's useful to have well-defined SI metric prefix to be used
to self-describe the formulas or equations.

List most popular ones in the units.h.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 include/linux/units.h | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/include/linux/units.h b/include/linux/units.h
index dcc30a53fa93..7366fcd45ec2 100644
--- a/include/linux/units.h
+++ b/include/linux/units.h
@@ -4,6 +4,22 @@
 
 #include <linux/math.h>
 
+/* Metric prefixes in accordance with Système international (d'unités) */
+#define PETA	1000000000000000LL
+#define TERA	1000000000000LL
+#define GIGA	1000000000L
+#define MEGA	1000000L
+#define KILO	1000L
+#define HECTO	100L
+#define DECA	10L
+#define DECI	10L
+#define CENTI	100L
+#define MILLI	1000L
+#define MICRO	1000000L
+#define NANO	1000000000L
+#define PICO	1000000000000LL
+#define FEMTO	1000000000000000LL
+
 #define MILLIWATT_PER_WATT	1000L
 #define MICROWATT_PER_MILLIWATT	1000L
 #define MICROWATT_PER_WATT	1000000L
-- 
2.30.2

[PATCH resend v1 2/3] i2c: designware: Use DIV_ROUND_CLOSEST() macro

[Andy Shevchenko]

Instead of open-coding DIV_ROUND_CLOSEST() and similar use the macros directly.
While at it, replace numbers with predefined SI metric prefixes.

No functional change intended.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-common.c  | 8 ++++----
 drivers/i2c/busses/i2c-designware-platdrv.c | 6 +++---
 2 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-common.c b/drivers/i2c/busses/i2c-designware-common.c
index fdc34d9e3702..9df101d1a34f 100644
--- a/drivers/i2c/busses/i2c-designware-common.c
+++ b/drivers/i2c/busses/i2c-designware-common.c
@@ -24,6 +24,7 @@
 #include <linux/regmap.h>
 #include <linux/swab.h>
 #include <linux/types.h>
+#include <linux/units.h>
 
 #include "i2c-designware-core.h"
 
@@ -350,7 +351,7 @@ u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
 		 *
 		 * If your hardware is free from tHD;STA issue, try this one.
 		 */
-		return (ic_clk * tSYMBOL + 500000) / 1000000 - 8 + offset;
+		return DIV_ROUND_CLOSEST(ic_clk * tSYMBOL, MEGA) - 8 + offset;
 	else
 		/*
 		 * Conditional expression:
@@ -366,8 +367,7 @@ u32 i2c_dw_scl_hcnt(u32 ic_clk, u32 tSYMBOL, u32 tf, int cond, int offset)
 		 * The reason why we need to take into account "tf" here,
 		 * is the same as described in i2c_dw_scl_lcnt().
 		 */
-		return (ic_clk * (tSYMBOL + tf) + 500000) / 1000000
-			- 3 + offset;
+		return DIV_ROUND_CLOSEST(ic_clk * (tSYMBOL + tf), MEGA) - 3 + offset;
 }
 
 u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
@@ -383,7 +383,7 @@ u32 i2c_dw_scl_lcnt(u32 ic_clk, u32 tLOW, u32 tf, int offset)
 	 * account the fall time of SCL signal (tf).  Default tf value
 	 * should be 0.3 us, for safety.
 	 */
-	return ((ic_clk * (tLOW + tf) + 500000) / 1000000) - 1 + offset;
+	return DIV_ROUND_CLOSEST(ic_clk * (tLOW + tf), MEGA) - 1 + offset;
 }
 
 int i2c_dw_set_sda_hold(struct dw_i2c_dev *dev)
diff --git a/drivers/i2c/busses/i2c-designware-platdrv.c b/drivers/i2c/busses/i2c-designware-platdrv.c
index 4b37f28ec0c6..099e303d22bb 100644
--- a/drivers/i2c/busses/i2c-designware-platdrv.c
+++ b/drivers/i2c/busses/i2c-designware-platdrv.c
@@ -31,12 +31,13 @@
 #include <linux/sched.h>
 #include <linux/slab.h>
 #include <linux/suspend.h>
+#include <linux/units.h>
 
 #include "i2c-designware-core.h"
 
 static u32 i2c_dw_get_clk_rate_khz(struct dw_i2c_dev *dev)
 {
-	return clk_get_rate(dev->clk)/1000;
+	return clk_get_rate(dev->clk) / KILO;
 }
 
 #ifdef CONFIG_ACPI
@@ -269,8 +270,7 @@ static int dw_i2c_plat_probe(struct platform_device *pdev)
 		clk_khz = dev->get_clk_rate_khz(dev);
 
 		if (!dev->sda_hold_time && t->sda_hold_ns)
-			dev->sda_hold_time =
-				div_u64(clk_khz * t->sda_hold_ns + 500000, 1000000);
+			dev->sda_hold_time = DIV_S64_ROUND_CLOSEST(clk_khz * t->sda_hold_ns, MEGA);
 	}
 
 	adap = &dev->adapter;
-- 
2.30.2

[PATCH resend v1 3/3] i2c: designware: Fix indentation in the header

[Andy Shevchenko]

In couple of places the indentation makes harder to read the code.
Fix it to be sane.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
---
 drivers/i2c/busses/i2c-designware-core.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-designware-core.h b/drivers/i2c/busses/i2c-designware-core.h
index 6a53f75abf7c..60a2e750cee9 100644
--- a/drivers/i2c/busses/i2c-designware-core.h
+++ b/drivers/i2c/busses/i2c-designware-core.h
@@ -117,7 +117,7 @@
 
 #define DW_IC_ERR_TX_ABRT	0x1
 
-#define DW_IC_TAR_10BITADDR_MASTER BIT(12)
+#define DW_IC_TAR_10BITADDR_MASTER	BIT(12)
 
 #define DW_IC_COMP_PARAM_1_SPEED_MODE_HIGH	(BIT(2) | BIT(3))
 #define DW_IC_COMP_PARAM_1_SPEED_MODE_MASK	GENMASK(3, 2)
@@ -245,7 +245,7 @@ struct dw_i2c_dev {
 	struct clk		*clk;
 	struct clk		*pclk;
 	struct reset_control	*rst;
-	struct i2c_client		*slave;
+	struct i2c_client	*slave;
 	u32			(*get_clk_rate_khz) (struct dw_i2c_dev *dev);
 	int			cmd_err;
 	struct i2c_msg		*msgs;
-- 
2.30.2

Re: [PATCH resend v1 1/3] units: Add SI metric prefix definitions

[Jarkko Nikula]

On 6/3/21 7:04 PM, Andy Shevchenko wrote:
> Sometimes it's useful to have well-defined SI metric prefix to be used
> to self-describe the formulas or equations.
> 
> List most popular ones in the units.h.
> 
> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
> ---
>   include/linux/units.h | 16 ++++++++++++++++
>   1 file changed, 16 insertions(+)
> 
> diff --git a/include/linux/units.h b/include/linux/units.h
> index dcc30a53fa93..7366fcd45ec2 100644
> --- a/include/linux/units.h
> +++ b/include/linux/units.h
> @@ -4,6 +4,22 @@
>   
>   #include <linux/math.h>
>   
> +/* Metric prefixes in accordance with Système international (d'unités) */
> +#define PETA	1000000000000000LL
> +#define TERA	1000000000000LL
> +#define GIGA	1000000000L
> +#define MEGA	1000000L
> +#define KILO	1000L
> +#define HECTO	100L
> +#define DECA	10L
> +#define DECI	10L
> +#define CENTI	100L
> +#define MILLI	1000L
> +#define MICRO	1000000L
> +#define NANO	1000000000L
> +#define PICO	1000000000000LL
> +#define FEMTO	1000000000000000LL
> +

For me milli is always 1/1000. Might lead to confusion with these 
defines if idea is to multiply with KILO but divide with MILLI?

Jarkko

Re: [PATCH resend v1 1/3] units: Add SI metric prefix definitions

[Andy Shevchenko]

On Mon, Jun 07, 2021 at 03:33:31PM +0300, Jarkko Nikula wrote:
> On 6/3/21 7:04 PM, Andy Shevchenko wrote:
> > Sometimes it's useful to have well-defined SI metric prefix to be used
> > to self-describe the formulas or equations.
> > 
> > List most popular ones in the units.h.

...

> > +/* Metric prefixes in accordance with Système international (d'unités) */
> > +#define PETA	1000000000000000LL
> > +#define TERA	1000000000000LL
> > +#define GIGA	1000000000L
> > +#define MEGA	1000000L
> > +#define KILO	1000L
> > +#define HECTO	100L
> > +#define DECA	10L
> > +#define DECI	10L
> > +#define CENTI	100L
> > +#define MILLI	1000L
> > +#define MICRO	1000000L
> > +#define NANO	1000000000L
> > +#define PICO	1000000000000LL
> > +#define FEMTO	1000000000000000LL
> 
> For me milli is always 1/1000.

For me as well. Kernel does not operate with float point numbers.
That's why it's ordered like this.

> Might lead to confusion with these defines if
> idea is to multiply with KILO but divide with MILLI?

If the author of the hypothetical driver doesn't understand this, maybe
they can ask first, but I am an optimist here and I assume that whoever
writes the driver for a sensor / etc has a minimum education to see
what's needed for the certain case.

-- 
With Best Regards,
Andy Shevchenko

Re: [PATCH resend v1 1/3] units: Add SI metric prefix definitions

[Andy Shevchenko]

On Mon, Jun 07, 2021 at 05:24:44PM +0300, Andy Shevchenko wrote:
> On Mon, Jun 07, 2021 at 03:33:31PM +0300, Jarkko Nikula wrote:
> > On 6/3/21 7:04 PM, Andy Shevchenko wrote:
> > > Sometimes it's useful to have well-defined SI metric prefix to be used
> > > to self-describe the formulas or equations.
> > > 
> > > List most popular ones in the units.h.
> 
> ...
> 
> > > +/* Metric prefixes in accordance with Système international (d'unités) */
> > > +#define PETA	1000000000000000LL
> > > +#define TERA	1000000000000LL
> > > +#define GIGA	1000000000L
> > > +#define MEGA	1000000L
> > > +#define KILO	1000L
> > > +#define HECTO	100L
> > > +#define DECA	10L
> > > +#define DECI	10L
> > > +#define CENTI	100L
> > > +#define MILLI	1000L
> > > +#define MICRO	1000000L
> > > +#define NANO	1000000000L
> > > +#define PICO	1000000000000LL
> > > +#define FEMTO	1000000000000000LL
> > 
> > For me milli is always 1/1000.
> 
> For me as well. Kernel does not operate with float point numbers.
> That's why it's ordered like this.
> 
> > Might lead to confusion with these defines if
> > idea is to multiply with KILO but divide with MILLI?
> 
> If the author of the hypothetical driver doesn't understand this, maybe
> they can ask first, but I am an optimist here and I assume that whoever
> writes the driver for a sensor / etc has a minimum education to see
> what's needed for the certain case.

Writing this, I think that I'm not so educated :-)

What we have in I²C case is kHz * ns = 10^3 * 10^-9, so we need to divide by
10^-6 to normalize the numbers. Sounds like MICRO is the correct thing to use
there.

-- 
With Best Regards,
Andy Shevchenko