[PATCH RFT v2 09/14] clk: qcom: smd-rpm: Add support for keepalive votes

Konrad Dybcio
2023-03-08T21:36:20Z

Some bus clock should always have a minimum (19.2 MHz) vote cast on
them, otherwise the platform will fall apart, hang and reboot.

Add support for specifying which clocks should be kept alive and
always keep a vote on XO_A to make sure the clock tree doesn't
collapse. This removes the need to keep a maximum vote that was
previously guaranteed by clk_smd_rpm_handoff.

This commit is a combination of existing (not-exactly-upstream) work
by Taniya Das, Shawn Guo and myself.

Co-developed-by: Shawn Guo <shawn.guo@linaro.org>
Co-developed-by: Taniya Das <quic_tdas@quicinc.com>
Signed-off-by: Konrad Dybcio <konrad.dybcio@linaro.org>
---
drivers/clk/qcom/clk-smd-rpm.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/drivers/clk/qcom/clk-smd-rpm.c b/drivers/clk/qcom/clk-smd-rpm.c
index eb7781e5c8c1..d89918f9ae60 100644
--- a/drivers/clk/qcom/clk-smd-rpm.c
+++ b/drivers/clk/qcom/clk-smd-rpm.c
@@ -45,15 +45,17 @@
}, \
}; \
__DEFINE_CLK_SMD_RPM_AO_PREFIX(_prefix, _name, _active, type, \
- r_id, key, ao_flags)
+ r_id, key, ao_flags, false)

#define __DEFINE_CLK_SMD_RPM_AO_PREFIX(_prefix, _name, _active, \
- type, r_id, key, ao_flags) \
+ type, r_id, key, ao_flags, \
+ _keep_alive) \
static struct clk_smd_rpm clk_smd_rpm_##_prefix##_active = { \
.rpm_res_type = (type), \
.rpm_clk_id = (r_id), \
.active_only = true, \
.rpm_key = (key), \
+ .keep_alive = (_keep_alive), \
.peer = &clk_smd_rpm_##_prefix##_name, \
.rate = INT_MAX, \
.hw.init = &(struct clk_init_data){ \
@@ -170,6 +172,7 @@ struct clk_smd_rpm {
const bool active_only;
bool enabled;
bool branch;
+ bool keep_alive;
struct clk_smd_rpm *peer;
struct clk_hw hw;
unsigned long rate;
@@ -198,11 +201,16 @@ static int clk_smd_rpm_handoff(struct clk_smd_rpm *r)
.value = cpu_to_le32(r->branch ? 1 : INT_MAX),
};

+ /* Set up keepalive clocks with a minimum bus rate */
+ if (r->keep_alive)
+ req.value = cpu_to_le32(19200); /* 19.2 MHz */
+
ret = qcom_rpm_smd_write(r->rpm, QCOM_SMD_RPM_ACTIVE_STATE,
r->rpm_res_type, r->rpm_clk_id, &req,
sizeof(req));
if (ret)
return ret;
+
ret = qcom_rpm_smd_write(r->rpm, QCOM_SMD_RPM_SLEEP_STATE,
r->rpm_res_type, r->rpm_clk_id, &req,
sizeof(req));
@@ -438,12 +446,29 @@ static int clk_smd_rpm_is_enabled(struct clk_hw *hw)
return r->enabled;
}

+static int clk_smd_rpm_determine_rate(struct clk_hw *hw,
+ struct clk_rate_request *req)
+{
+ struct clk_smd_rpm *r = to_clk_smd_rpm(hw);
+
+ /*
+ * RPM resolves the rates internally. All we have to do on the kernel
+ * side is ensure that we don't accidentally put down the keepalive
+ * clocks, which could happen if they received a vote below 19.2 MHz.
+ */
+ if (r->keep_alive)
+ req->rate = max(req->rate, 19200000UL);
+
+ return 0;
+}
+
static const struct clk_ops clk_smd_rpm_ops = {
.prepare = clk_smd_rpm_prepare,
.unprepare = clk_smd_rpm_unprepare,
.set_rate = clk_smd_rpm_set_rate,
.round_rate = clk_smd_rpm_round_rate,
.recalc_rate = clk_smd_rpm_recalc_rate,
+ .determine_rate = clk_smd_rpm_determine_rate,
.is_enabled = clk_smd_rpm_is_enabled,
.is_prepared = clk_smd_rpm_is_enabled,
};

--
2.39.2