Re: [PATCH 3/7] phy: qcom: qmp-pcie: register second optional PHY AUX clock
From: neil . armstrong
Date: Tue Mar 19 2024 - 11:10:32 EST
On 19/03/2024 15:46, Dmitry Baryshkov wrote:
On Tue, 19 Mar 2024 at 16:35, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
On 19/03/2024 11:59, Neil Armstrong wrote:
On 19/03/2024 11:55, Dmitry Baryshkov wrote:
On Tue, 19 Mar 2024 at 12:45, Neil Armstrong <neil.armstrong@xxxxxxxxxx> wrote:
The PCIe Gen4x2 PHY found in the SM8[456]50 SoCs have a second clock,
add the code to register it for PHYs configs that sets a aux_clock_rate.
In order to get the right clock, add qmp_pcie_clk_hw_get() which uses
the newly introduced QMP_PCIE_PIPE_CLK & QMP_PCIE_PHY_AUX_CLK clock
IDs and also supports the legacy bindings by returning the PIPE clock.
Signed-off-by: Neil Armstrong <neil.armstrong@xxxxxxxxxx>
---
drivers/phy/qualcomm/phy-qcom-qmp-pcie.c | 70 ++++++++++++++++++++++++++++++++
1 file changed, 70 insertions(+)
diff --git a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
index 079b3e306489..2d05226ae200 100644
--- a/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
+++ b/drivers/phy/qualcomm/phy-qcom-qmp-pcie.c
@@ -22,6 +22,8 @@
#include <linux/reset.h>
#include <linux/slab.h>
+#include <dt-bindings/phy/phy-qcom-qmp.h>
+
#include "phy-qcom-qmp-common.h"
#include "phy-qcom-qmp.h"
@@ -2389,6 +2391,9 @@ struct qmp_phy_cfg {
/* QMP PHY pipe clock interface rate */
unsigned long pipe_clock_rate;
+
+ /* QMP PHY AUX clock interface rate */
+ unsigned long aux_clock_rate;
};
struct qmp_pcie {
@@ -2420,6 +2425,7 @@ struct qmp_pcie {
int mode;
struct clk_fixed_rate pipe_clk_fixed;
+ struct clk_fixed_rate aux_clk_fixed;
};
static inline void qphy_setbits(void __iomem *base, u32 offset, u32 val)
@@ -3681,6 +3687,62 @@ static int phy_pipe_clk_register(struct qmp_pcie *qmp, struct device_node *np)
return devm_clk_hw_register(qmp->dev, &fixed->hw);
}
+/*
+ * Register a fixed rate PHY aux clock.
+ *
+ * The <s>_phy_aux_clksrc generated by PHY goes to the GCC that gate
+ * controls it. The <s>_phy_aux_clk coming out of the GCC is requested
+ * by the PHY driver for its operations.
+ * We register the <s>_phy_aux_clksrc here. The gcc driver takes care
+ * of assigning this <s>_phy_aux_clksrc as parent to <s>_phy_aux_clk.
+ * Below picture shows this relationship.
+ *
+ * +---------------+
+ * | PHY block |<<---------------------------------------------+
+ * | | |
+ * | +-------+ | +-----+ |
+ * I/P---^-->| PLL |---^--->phy_aux_clksrc--->| GCC |--->phy_aux_clk---+
+ * clk | +-------+ | +-----+
+ * +---------------+
+ */
+static int phy_aux_clk_register(struct qmp_pcie *qmp, struct device_node *np)
+{
+ struct clk_fixed_rate *fixed = &qmp->aux_clk_fixed;
+ struct clk_init_data init = { };
+ int ret;
+
+ ret = of_property_read_string_index(np, "clock-output-names", 1, &init.name);
+ if (ret) {
+ dev_err(qmp->dev, "%pOFn: No clock-output-names index 1\n", np);
+ return ret;
+ }
+
+ init.ops = &clk_fixed_rate_ops;
+
+ fixed->fixed_rate = qmp->cfg->aux_clock_rate;
+ fixed->hw.init = &init;
+
+ return devm_clk_hw_register(qmp->dev, &fixed->hw);
+}
+
+static struct clk_hw *qmp_pcie_clk_hw_get(struct of_phandle_args *clkspec, void *data)
+{
+ struct qmp_pcie *qmp = data;
+
+ /* Support legacy bindings */
+ if (!clkspec->args_count)
+ return &qmp->pipe_clk_fixed.hw;
+
+ switch (clkspec->args[0]) {
+ case QMP_PCIE_PIPE_CLK:
+ return &qmp->pipe_clk_fixed.hw;
+ case QMP_PCIE_PHY_AUX_CLK:
+ return &qmp->aux_clk_fixed.hw;
+ }
+
+ return ERR_PTR(-EINVAL);
+}
Can we use of_clk_hw_onecell_get() instead? I think it even should be
possible to use onecell for both cases, it will look at the first arg,
which will be 0 in case of #clock-cells equal to 0.
I didn't find evidence this is the case, while following of_parse_clkspec() called
from of_clk_get_hw() or clk_core_get(), where clkspec is not initialized, the
__of_parse_phandle_with_args() and of_phandle_iterator_args() don't touch
clkspec->args if it->cur_count is 0. So clkspec->args[0] may be left initialized
and it would be abusingthe API to use it with #clocks-cells = 0.
Let me investigate if it's possible
Ok, it would work but it would require building a clk_hw_onecell_data a runtime,
while we could simply provide this qmp_pcie_clk_hw_get() and avoid runtime 2 allocations.
I'm not sure it's worth it.
Single allocation (or even 0 allocations if you embed it into struct
qmp_pcie) for the sake of using standard helpers.
Well, sure
Thanks,
Neil