* [PATCH v3 1/3] dt-bindings: clock: ti: dpll: deprecate the ti,ssc-* properties
2026-10-28 7:44 [PATCH v3 0/3] clk: ti: dpll: switch spread spectrum to the generic framework Dario Binacchi
@ 2026-10-28 7:44 ` Dario Binacchi
2026-10-28 11:11 ` Krzysztof Kozlowski
2026-10-28 7:44 ` [PATCH v3 2/3] clk: ti: dpll: use the generic spread spectrum configuration Dario Binacchi
2026-10-28 7:44 ` [PATCH v3 3/3] clk: ti: dpll: apply the spread spectrum configuration right away Dario Binacchi
2 siblings, 1 reply; 5+ messages in thread
From: Dario Binacchi @ 2026-10-28 7:44 UTC (permalink / raw)
To: linux-kernel
Cc: linux-amarula, michael, Dario Binacchi, Brian Masney,
Conor Dooley, Jerome Brunet, Krzysztof Kozlowski, Rob Herring,
Stephen Boyd, devicetree, linux-clk
The common clock binding provides assigned-clock-sscs to configure
spread spectrum clocking (SSC), supported by the clock core since commit
a7f16660af39 ("clk: conf: Support assigned-clock-sscs"). Deprecate the
vendor specific ti,ssc-deltam, ti,ssc-modfreq-hz and ti,ssc-downspread
properties in favor of it, so that new DTs use a single way to describe
the same thing.
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---
Changes in v3:
- Deprecate the properties instead of dropping them
Documentation/devicetree/bindings/clock/ti/dpll.txt | 9 ++++++---
1 file changed, 6 insertions(+), 3 deletions(-)
diff --git a/Documentation/devicetree/bindings/clock/ti/dpll.txt b/Documentation/devicetree/bindings/clock/ti/dpll.txt
index 14a1b72c2e71..8759c328e841 100644
--- a/Documentation/devicetree/bindings/clock/ti/dpll.txt
+++ b/Documentation/devicetree/bindings/clock/ti/dpll.txt
@@ -57,11 +57,14 @@ Optional properties:
- ti,min-div : the minimum divisor to start from to round the DPLL
target rate
- ti,ssc-deltam : DPLL supports spread spectrum clocking, frequency
- spreading in permille (10th of a percent)
+ spreading in permille (10th of a percent).
+ Deprecated, use assigned-clock-sscs instead.
- ti,ssc-modfreq-hz : DPLL supports spread spectrum clocking, spread
- spectrum modulation frequency
+ spectrum modulation frequency.
+ Deprecated, use assigned-clock-sscs instead.
- ti,ssc-downspread : DPLL supports spread spectrum clocking, boolean
- to enable the downspread feature
+ to enable the downspread feature.
+ Deprecated, use assigned-clock-sscs instead.
Examples:
dpll_core_ck: dpll_core_ck@44e00490 {
--
2.43.0
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v3 2/3] clk: ti: dpll: use the generic spread spectrum configuration
2026-10-28 7:44 [PATCH v3 0/3] clk: ti: dpll: switch spread spectrum to the generic framework Dario Binacchi
2026-10-28 7:44 ` [PATCH v3 1/3] dt-bindings: clock: ti: dpll: deprecate the ti,ssc-* properties Dario Binacchi
@ 2026-10-28 7:44 ` Dario Binacchi
2026-10-28 7:44 ` [PATCH v3 3/3] clk: ti: dpll: apply the spread spectrum configuration right away Dario Binacchi
2 siblings, 0 replies; 5+ messages in thread
From: Dario Binacchi @ 2026-10-28 7:44 UTC (permalink / raw)
To: linux-kernel
Cc: linux-amarula, michael, Dario Binacchi, Brian Masney,
Jerome Brunet, Stephen Boyd, Tero Kristo, linux-clk, linux-omap
The clock framework provides a generic API and DT property for spread
spectrum clocking (SSC) since commit c86814e70390 ("clk: Introduce
clk_hw_set_spread_spectrum"). Implement the set_spread_spectrum callback
and convert the deprecated vendor specific properties to the generic
configuration, so that existing DTs keep working.
The SSC registers are programmed at the next rate change, as with the
vendor specific properties. The generic framework expresses the spread
in permyriad rather than permille, hence the change in the deltaM step
computation, and also supports up-spread, which is rejected as the
hardware does not support it.
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---
Changes in v3:
- Keep parsing the deprecated vendor specific properties
drivers/clk/ti/clock.h | 2 ++
drivers/clk/ti/dpll.c | 20 +++++++++----
drivers/clk/ti/dpll3xxx.c | 61 ++++++++++++++++++++++++++++++++-------
include/linux/clk/ti.h | 9 ++----
4 files changed, 70 insertions(+), 22 deletions(-)
diff --git a/drivers/clk/ti/clock.h b/drivers/clk/ti/clock.h
index d5e24fe4ae3a..83225e506314 100644
--- a/drivers/clk/ti/clock.h
+++ b/drivers/clk/ti/clock.h
@@ -271,6 +271,8 @@ int omap3_noncore_dpll_set_rate_and_parent(struct clk_hw *hw,
unsigned long rate,
unsigned long parent_rate,
u8 index);
+int omap3_noncore_dpll_set_spread_spectrum(struct clk_hw *hw,
+ const struct clk_spread_spectrum *ss_conf);
int omap3_noncore_dpll_determine_rate(struct clk_hw *hw,
struct clk_rate_request *req);
int omap2_dpll_determine_rate(struct clk_hw *hw, struct clk_rate_request *req);
diff --git a/drivers/clk/ti/dpll.c b/drivers/clk/ti/dpll.c
index e01272cd628d..1329b4bc02f0 100644
--- a/drivers/clk/ti/dpll.c
+++ b/drivers/clk/ti/dpll.c
@@ -51,6 +51,7 @@ static const struct clk_ops dpll_ck_ops = {
.set_parent = &omap3_noncore_dpll_set_parent,
.set_rate_and_parent = &omap3_noncore_dpll_set_rate_and_parent,
.determine_rate = &omap3_noncore_dpll_determine_rate,
+ .set_spread_spectrum = &omap3_noncore_dpll_set_spread_spectrum,
.get_parent = &omap2_init_dpll_parent,
.save_context = &omap3_noncore_dpll_save_context,
.restore_context = &omap3_noncore_dpll_restore_context,
@@ -63,6 +64,7 @@ static const struct clk_ops dpll_no_gate_ck_ops = {
.set_parent = &omap3_noncore_dpll_set_parent,
.set_rate_and_parent = &omap3_noncore_dpll_set_rate_and_parent,
.determine_rate = &omap3_noncore_dpll_determine_rate,
+ .set_spread_spectrum = &omap3_noncore_dpll_set_spread_spectrum,
.save_context = &omap3_noncore_dpll_save_context,
.restore_context = &omap3_noncore_dpll_restore_context
};
@@ -278,6 +280,7 @@ static void __init of_ti_dpll_setup(struct device_node *node,
struct dpll_data *dd = NULL;
int ssc_clk_index;
u8 dpll_mode = 0;
+ u32 ssc_modfreq = 0, ssc_deltam = 0;
u32 min_div;
dd = kmemdup(ddt, sizeof(*dd), GFP_KERNEL);
@@ -349,11 +352,18 @@ static void __init of_ti_dpll_setup(struct device_node *node,
&dd->ssc_modfreq_reg))
goto cleanup;
- of_property_read_u32(node, "ti,ssc-modfreq-hz",
- &dd->ssc_modfreq);
- of_property_read_u32(node, "ti,ssc-deltam", &dd->ssc_deltam);
- dd->ssc_downspread =
- of_property_read_bool(node, "ti,ssc-downspread");
+ /* Deprecated, superseded by assigned-clock-sscs */
+ of_property_read_u32(node, "ti,ssc-modfreq-hz", &ssc_modfreq);
+ of_property_read_u32(node, "ti,ssc-deltam", &ssc_deltam);
+ if (ssc_modfreq && ssc_deltam) {
+ dd->ssc_conf.modfreq_hz = ssc_modfreq;
+ /* permille to permyriad */
+ dd->ssc_conf.spread_bp = ssc_deltam * 10;
+ if (of_property_read_bool(node, "ti,ssc-downspread"))
+ dd->ssc_conf.method = CLK_SPREAD_DOWN;
+ else
+ dd->ssc_conf.method = CLK_SPREAD_CENTER;
+ }
}
if (of_property_read_bool(node, "ti,low-power-stop"))
diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c
index 8c51b988a04f..634fe0a1f9fd 100644
--- a/drivers/clk/ti/dpll3xxx.c
+++ b/drivers/clk/ti/dpll3xxx.c
@@ -295,30 +295,32 @@ static void _lookup_sddiv(struct clk_hw_omap *clk, u8 *sd_div, u16 m, u8 n)
* omap3_noncore_dpll_ssc_program - set spread-spectrum clocking registers
* @clk: struct clk * of DPLL to set
*
- * Enable the DPLL spread spectrum clocking if frequency modulation and
- * frequency spreading have been set, otherwise disable it.
+ * Enable the DPLL spread spectrum clocking according to the configuration
+ * set by omap3_noncore_dpll_set_spread_spectrum(), otherwise disable it.
*/
static void omap3_noncore_dpll_ssc_program(struct clk_hw_omap *clk)
{
struct dpll_data *dd = clk->dpll_data;
+ const struct clk_spread_spectrum *conf = &dd->ssc_conf;
+ bool downspread = conf->method == CLK_SPREAD_DOWN;
unsigned long ref_rate;
u32 v, ctrl, mod_freq_divider, exponent, mantissa;
u32 deltam_step, deltam_ceil;
ctrl = ti_clk_ll_ops->clk_readl(&dd->control_reg);
- if (dd->ssc_modfreq && dd->ssc_deltam) {
+ if (conf->method != CLK_SPREAD_NO) {
ctrl |= dd->ssc_enable_mask;
- if (dd->ssc_downspread)
+ if (downspread)
ctrl |= dd->ssc_downspread_mask;
else
ctrl &= ~dd->ssc_downspread_mask;
ref_rate = clk_hw_get_rate(dd->clk_ref);
mod_freq_divider =
- (ref_rate / dd->last_rounded_n) / (4 * dd->ssc_modfreq);
- if (dd->ssc_modfreq > (ref_rate / 70))
+ (ref_rate / dd->last_rounded_n) / (4 * conf->modfreq_hz);
+ if (conf->modfreq_hz > (ref_rate / 70))
pr_warn("clock: SSC modulation frequency of DPLL %s greater than %ld\n",
__clk_get_name(clk->hw.clk), ref_rate / 70);
@@ -337,9 +339,10 @@ static void omap3_noncore_dpll_ssc_program(struct clk_hw_omap *clk)
v |= exponent << __ffs(dd->ssc_modfreq_exp_mask);
ti_clk_ll_ops->clk_writel(v, &dd->ssc_modfreq_reg);
- deltam_step = dd->last_rounded_m * dd->ssc_deltam;
- deltam_step /= 10;
- if (dd->ssc_downspread)
+ /* spread_bp is in permyriad, convert to percent first */
+ deltam_step = dd->last_rounded_m * conf->spread_bp;
+ deltam_step /= 100;
+ if (downspread)
deltam_step /= 2;
deltam_step <<= __ffs(dd->ssc_deltam_int_mask);
@@ -353,7 +356,7 @@ static void omap3_noncore_dpll_ssc_program(struct clk_hw_omap *clk)
if (deltam_step & dd->ssc_deltam_frac_mask)
deltam_ceil++;
- if ((dd->ssc_downspread &&
+ if ((downspread &&
((dd->last_rounded_m - (2 * deltam_ceil)) < 20 ||
dd->last_rounded_m > 2045)) ||
((dd->last_rounded_m - deltam_ceil) < 20 ||
@@ -682,6 +685,44 @@ int omap3_noncore_dpll_set_rate(struct clk_hw *hw, unsigned long rate,
return ret;
}
+/**
+ * omap3_noncore_dpll_set_spread_spectrum - set the DPLL SSC configuration
+ * @hw: pointer to the clock to set the spread spectrum configuration for
+ * @ss_conf: spread spectrum configuration
+ *
+ * Stores the spread spectrum clocking (SSC) configuration of the DPLL. The
+ * configuration is programmed along with the DPLL multiplier and divider
+ * at the next rate change. The hardware supports center-spread and
+ * down-spread only. Returns 0 on success, or a negative error value on
+ * failure.
+ */
+int omap3_noncore_dpll_set_spread_spectrum(struct clk_hw *hw,
+ const struct clk_spread_spectrum *ss_conf)
+{
+ struct clk_hw_omap *clk = to_clk_hw_omap(hw);
+ struct dpll_data *dd = clk->dpll_data;
+
+ if (!dd || !dd->ssc_enable_mask)
+ return -EOPNOTSUPP;
+
+ switch (ss_conf->method) {
+ case CLK_SPREAD_NO:
+ break;
+ case CLK_SPREAD_CENTER:
+ case CLK_SPREAD_DOWN:
+ if (!ss_conf->modfreq_hz || !ss_conf->spread_bp)
+ return -EINVAL;
+ break;
+ default:
+ /* Up-spread is not supported by the hardware */
+ return -EINVAL;
+ }
+
+ dd->ssc_conf = *ss_conf;
+
+ return 0;
+}
+
/**
* omap3_noncore_dpll_set_rate_and_parent - set rate and parent for a DPLL clock
* @hw: pointer to the clock to set rate and parent for
diff --git a/include/linux/clk/ti.h b/include/linux/clk/ti.h
index 54a3fa370004..107056120c2c 100644
--- a/include/linux/clk/ti.h
+++ b/include/linux/clk/ti.h
@@ -65,10 +65,7 @@ struct clk_omap_reg {
* @ssc_enable_mask: mask of the DPLL SSC enable bit in @control_reg
* @ssc_downspread_mask: mask of the DPLL SSC low frequency only bit in
* @control_reg
- * @ssc_modfreq: the DPLL SSC frequency modulation in kHz
- * @ssc_deltam: the DPLL SSC frequency spreading in permille (10th of percent)
- * @ssc_downspread: require the only low frequency spread of the DPLL in SSC
- * mode
+ * @ssc_conf: the DPLL SSC configuration
* @flags: DPLL type/features (see below)
*
* Possible values for @flags:
@@ -124,9 +121,7 @@ struct dpll_data {
u32 ssc_modfreq_exp_mask;
u32 ssc_enable_mask;
u32 ssc_downspread_mask;
- u32 ssc_modfreq;
- u32 ssc_deltam;
- bool ssc_downspread;
+ struct clk_spread_spectrum ssc_conf;
u8 flags;
};
--
2.43.0
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v3 3/3] clk: ti: dpll: apply the spread spectrum configuration right away
2026-10-28 7:44 [PATCH v3 0/3] clk: ti: dpll: switch spread spectrum to the generic framework Dario Binacchi
2026-10-28 7:44 ` [PATCH v3 1/3] dt-bindings: clock: ti: dpll: deprecate the ti,ssc-* properties Dario Binacchi
2026-10-28 7:44 ` [PATCH v3 2/3] clk: ti: dpll: use the generic spread spectrum configuration Dario Binacchi
@ 2026-10-28 7:44 ` Dario Binacchi
2 siblings, 0 replies; 5+ messages in thread
From: Dario Binacchi @ 2026-10-28 7:44 UTC (permalink / raw)
To: linux-kernel
Cc: linux-amarula, michael, Dario Binacchi, Brian Masney,
Jerome Brunet, Stephen Boyd, Tero Kristo, linux-clk, linux-omap
The spread spectrum clocking (SSC) registers are only programmed by
set_rate(), which the clock core skips when the requested rate is
already the current one, e.g. when the bootloader has set it up.
As a result, the SSC configuration is not applied, as it was with the
vendor specific properties.
Apply it from set_spread_spectrum() instead, reprogramming the DPLL
at its current rate.
Signed-off-by: Dario Binacchi <dario.binacchi@amarulasolutions.com>
---
Changes in v3:
- Skip reprogramming only if the configuration is already applied
to the hardware
Changes in v2:
- Check the DPLL lock state instead of its parent, as the reference
and bypass clocks can be the same clock
drivers/clk/ti/dpll3xxx.c | 49 ++++++++++++++++++++++++++++++++++-----
1 file changed, 43 insertions(+), 6 deletions(-)
diff --git a/drivers/clk/ti/dpll3xxx.c b/drivers/clk/ti/dpll3xxx.c
index 634fe0a1f9fd..d32d81a27bfe 100644
--- a/drivers/clk/ti/dpll3xxx.c
+++ b/drivers/clk/ti/dpll3xxx.c
@@ -690,17 +690,22 @@ int omap3_noncore_dpll_set_rate(struct clk_hw *hw, unsigned long rate,
* @hw: pointer to the clock to set the spread spectrum configuration for
* @ss_conf: spread spectrum configuration
*
- * Stores the spread spectrum clocking (SSC) configuration of the DPLL. The
- * configuration is programmed along with the DPLL multiplier and divider
- * at the next rate change. The hardware supports center-spread and
- * down-spread only. Returns 0 on success, or a negative error value on
- * failure.
+ * Stores the spread spectrum clocking (SSC) configuration of the DPLL and,
+ * if the DPLL is locked, reprograms it at its current rate to apply it.
+ * Otherwise the configuration is applied at the next rate change. The
+ * hardware supports center-spread and down-spread only. Returns 0 on
+ * success, negative error value otherwise.
*/
int omap3_noncore_dpll_set_spread_spectrum(struct clk_hw *hw,
const struct clk_spread_spectrum *ss_conf)
{
struct clk_hw_omap *clk = to_clk_hw_omap(hw);
struct dpll_data *dd = clk->dpll_data;
+ struct clk_spread_spectrum old_conf;
+ struct clk_rate_request req;
+ unsigned long rate;
+ int ret;
+ u32 ctrl;
if (!dd || !dd->ssc_enable_mask)
return -EOPNOTSUPP;
@@ -718,9 +723,41 @@ int omap3_noncore_dpll_set_spread_spectrum(struct clk_hw *hw,
return -EINVAL;
}
+ ctrl = ti_clk_ll_ops->clk_readl(&dd->control_reg);
+
+ /* Already applied */
+ if (!memcmp(ss_conf, &dd->ssc_conf, sizeof(*ss_conf)) &&
+ !!(ctrl & dd->ssc_enable_mask) == (ss_conf->method != CLK_SPREAD_NO))
+ return 0;
+
+ old_conf = dd->ssc_conf;
dd->ssc_conf = *ss_conf;
- return 0;
+ /* Disabling SSC does not need to reprogram the DPLL */
+ if (ss_conf->method == CLK_SPREAD_NO) {
+ omap3_noncore_dpll_ssc_program(clk);
+ return 0;
+ }
+
+ /* Not locked: SSC is programmed along with the next rate change */
+ if (((ctrl & dd->enable_mask) >> __ffs(dd->enable_mask)) != DPLL_LOCKED)
+ return 0;
+
+ rate = clk_hw_get_rate(hw);
+ clk_hw_init_rate_request(hw, &req, rate);
+ ret = omap2_dpll_determine_rate(hw, &req);
+ if (!ret && req.rate != rate)
+ ret = -EINVAL;
+ if (!ret)
+ ret = omap3_noncore_dpll_set_rate(hw, rate,
+ clk_hw_get_rate(dd->clk_ref));
+ if (ret) {
+ pr_warn("clock: %s: rate %lu can't be kept with SSC enabled\n",
+ clk_hw_get_name(hw), rate);
+ dd->ssc_conf = old_conf;
+ }
+
+ return ret;
}
/**
--
2.43.0
^ permalink raw reply [flat|nested] 5+ messages in thread