clk: clk-si544: Simplify probe() and is_valid_frequency()

The driver has an OF match table, still, it uses an ID lookup table for
retrieving match data. Currently, the driver is working on the
assumption that an I2C device registered via OF will always match a
legacy I2C device ID. The correct approach is to have an OF device ID
table using i2c_get_match_data() if the devices are registered via OF/ID.

Unify the OF/ID table by using max_freq as match data instead of
enum si544_speed_grade and replace the ID lookup table for
the match data by i2c_get_match_data(). This allows to simplify both
probe() and is_valid_frequency().

Drop enum si544_speed_grade as there is no user.

While at it, remove the trailing comma in the terminator entry for the OF
table making code robust against (theoretical) misrebases or other similar
things where the new entry goes _after_ the termination without the
compiler noticing.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Link: https://lore.kernel.org/r/20230909155418.24426-1-biju.das.jz@bp.renesas.com
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: si544: Convert to use maple tree register cache

The maple tree register cache is based on a much more modern data structure
than the rbtree cache and makes optimisation choices which are probably
more appropriate for modern systems than those made by the rbtree cache.

Signed-off-by: Mark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20230929-clk-maple-si-v1-4-e26cfcaf27bd@kernel.org
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: Switch i2c drivers back to use .probe()

After commit b8a1a4cd5a98 ("i2c: Provide a temporary .probe_new()
call-back type"), all drivers being converted to .probe_new() and then
03c835f498b5 ("i2c: Switch .probe() to not take an id parameter") convert
back to (the new) .probe() to be able to eventually drop .probe_new() from
struct i2c_driver.

Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Link: https://lore.kernel.org/r/20230427125531.622202-1-u.kleine-koenig@pengutronix.de
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: si544: use i2c_match_id and simple i2c probe

As part of the ongoing i2c transition to the simple probe
("probe_new"), this patch uses i2c_match_id to retrieve the
driver_data for the probed device. The id parameter is thus no longer
necessary and the simple probe can be used instead.

Signed-off-by: Stephen Kitt <steve@sk2.org>
Link: https://lore.kernel.org/r/20220407151831.2371706-9-steve@sk2.org
Reviewed-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: clk-si544: Implement small frequency change support

The Si544 supports changing frequencies "on the fly" when the change is
less than 950 ppm from the current center frequency. The driver now
uses the small adjustment routine for implementing this.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk-si514, clk-si544: Implement prepare/unprepare/is_prepared operations

This adds prepare/unprepare/is_prepared functionality to the drivers for
the SI544 and SI514 chips, allowing the clock output to be disabled when
the clock is not in use.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk-si544: Properly round requested frequency to nearest match

The si544 driver had a rounding problem that using the result of clk_round_rate
may set the clock to yet another rate, for example:
clk_round_rate(195000000) = 194999999
clk_round_rate(194999999) = 194999998

Clients would expect that after clk_set_rate(clk, freq2=clk_round_rate(clk, freq)) the
chip will be running at exactly freq2.

The problem was in the calculation of the feedback divider, it was always rounded
down instead of to the nearest possible VCO value.

After this change, the following holds true for any supported frequency:
actual_freq = clk_round_rate(clk, freq);
clk_set_rate(clk, actual_freq);
clk_round_rate(clk, actual_freq) == actual_freq && clk_get_rate(clk) == actual_freq

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
Fixes: 953cc3e81170 ("clk: Add driver for the si544 clock generator chip")
Signed-off-by: Stephen Boyd <sboyd@kernel.org>

clk: Add driver for the si544 clock generator chip

This patch adds the driver and devicetree documentation for the
Silicon Labs SI544 clock generator chip. This is an I2C controlled
oscillator capable of generating clock signals ranging from 200kHz
to 1500MHz.

Signed-off-by: Mike Looijmans <mike.looijmans@topic.nl>
[sboyd: assign max_freq to 0 in is_valid_frequency() to squelch warning]
Signed-off-by: Stephen Boyd <sboyd@kernel.org>