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net: ethernet: ti: cpts: calc mult and shift from refclk freq 

The cyclecounter mult and shift values can be calculated based on the
CPTS rfclk frequency and timekeepnig framework provides required algos
and API's.

Hence, calc mult and shift basing on CPTS rfclk frequency if both
cpts_clock_shift and cpts_clock_mult properties are not provided in DT (the
basis of calculation algorithm is borrowed from
__clocksource_update_freq_scale() commit 7d2f944a2b ("clocksource:
Provide a generic mult/shift factor calculation")). After this change
cpts_clock_shift and cpts_clock_mult DT properties will become optional.

Cc: John Stultz <john.stultz@linaro.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Grygorii Strashko <grygorii.strashko@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Grygorii Strashko 2016-12-06 18:00:44 -06:00 committed by David S. Miller
parent 5304121ada
commit 88f0f0b0be
2 changed files with 48 additions and 10 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
Documentation/devicetree/bindings/net/cpsw.txt
View File

@ -20,8 +20,6 @@ Required properties:
- slaves : Specifies number for slaves
- active_slave : Specifies the slave to use for time stamping,
ethtool and SIOCGMIIPHY
- cpts_clock_mult : Numerator to convert input clock ticks into nanoseconds
- cpts_clock_shift : Denominator to convert input clock ticks into nanoseconds
Optional properties:
- ti,hwmods : Must be "cpgmac0"
@ -35,7 +33,11 @@ Optional properties:
For example in dra72x-evm, pcf gpio has to be
driven low so that cpsw slave 0 and phy data
lines are connected via mux.
- cpts_clock_mult : Numerator to convert input clock ticks into nanoseconds
- cpts_clock_shift : Denominator to convert input clock ticks into nanoseconds
Mult and shift will be calculated basing on CPTS
rftclk frequency if both cpts_clock_shift and
cpts_clock_mult properties are not provided.
Slave Properties:
Required properties:

50
drivers/net/ethernet/ti/cpts.c
View File

@ -405,18 +405,52 @@ void cpts_unregister(struct cpts *cpts)
}
EXPORT_SYMBOL_GPL(cpts_unregister);
static void cpts_calc_mult_shift(struct cpts *cpts)
{
u64 frac, maxsec, ns;
u32 freq;
freq = clk_get_rate(cpts->refclk);
/* Calc the maximum number of seconds which we can run before
* wrapping around.
*/
maxsec = cpts->cc.mask;
do_div(maxsec, freq);
/* limit conversation rate to 10 sec as higher values will produce
* too small mult factors and so reduce the conversion accuracy
*/
if (maxsec > 10)
maxsec = 10;
if (cpts->cc.mult || cpts->cc.shift)
return;
clocks_calc_mult_shift(&cpts->cc.mult, &cpts->cc.shift,
freq, NSEC_PER_SEC, maxsec);
frac = 0;
ns = cyclecounter_cyc2ns(&cpts->cc, freq, cpts->cc.mask, &frac);
dev_info(cpts->dev,
"CPTS: ref_clk_freq:%u calc_mult:%u calc_shift:%u error:%lld nsec/sec\n",
freq, cpts->cc.mult, cpts->cc.shift, (ns - NSEC_PER_SEC));
}
static int cpts_of_parse(struct cpts *cpts, struct device_node *node)
{
int ret = -EINVAL;
u32 prop;
if (of_property_read_u32(node, "cpts_clock_mult", &prop))
goto of_error;
cpts->cc.mult = prop;
if (!of_property_read_u32(node, "cpts_clock_mult", &prop))
cpts->cc.mult = prop;
if (of_property_read_u32(node, "cpts_clock_shift", &prop))
goto of_error;
cpts->cc.shift = prop;
if (!of_property_read_u32(node, "cpts_clock_shift", &prop))
cpts->cc.shift = prop;
if ((cpts->cc.mult && !cpts->cc.shift) ||
(!cpts->cc.mult && cpts->cc.shift))
goto of_error;
return 0;
@ -454,11 +488,13 @@ struct cpts *cpts_create(struct device *dev, void __iomem *regs,
cpts->cc.read = cpts_systim_read;
cpts->cc.mask = CLOCKSOURCE_MASK(32);
cpts->info = cpts_info;
cpts_calc_mult_shift(cpts);
/* save cc.mult original value as it can be modified
* by cpts_ptp_adjfreq().
*/
cpts->cc_mult = cpts->cc.mult;
cpts->info = cpts_info;
return cpts;
}