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SubjectRe: [PATCH v3 2/2] interconnect: qcom: Add OSM L3 interconnect provider support
Hey Evan,
Thanks for taking time to review
the series.

On 2019-11-19 04:12, Evan Green wrote:
> Hi Sibi,
>
> On Mon, Nov 18, 2019 at 7:45 AM Sibi Sankar <sibis@codeaurora.org>
> wrote:
>>
>> On some Qualcomm SoCs, Operating State Manager (OSM) controls the
>> resources of scaling L3 caches. Add a driver to handle bandwidth
>> requests to OSM L3 from CPU/GPU.
>>
>> Signed-off-by: Sibi Sankar <sibis@codeaurora.org>
>> ---
>> drivers/interconnect/qcom/Kconfig | 7 +
>> drivers/interconnect/qcom/Makefile | 2 +
>> drivers/interconnect/qcom/osm-l3.c | 284
>> +++++++++++++++++++++++++++++
>> 3 files changed, 293 insertions(+)
>> create mode 100644 drivers/interconnect/qcom/osm-l3.c
>>
>> diff --git a/drivers/interconnect/qcom/Kconfig
>> b/drivers/interconnect/qcom/Kconfig
>> index ecf057d7e2409..17aee5b0f15b7 100644
>> --- a/drivers/interconnect/qcom/Kconfig
>> +++ b/drivers/interconnect/qcom/Kconfig
>> @@ -5,6 +5,13 @@ config INTERCONNECT_QCOM
>> help
>> Support for Qualcomm's Network-on-Chip interconnect
>> hardware.
>>
>> +config INTERCONNECT_QCOM_OSM_L3
>> + tristate "Qualcomm OSM L3 interconnect driver"
>> + depends on INTERCONNECT_QCOM || COMPILE_TEST
>
> Should we depend on something sdm845 here?

not really...

maybe I can have 845 interconnect
selecting osm_l3? since sc7180 also
would be doing the same.

>
>> + help
>> + Say y here to support the Operating State Manager (OSM)
>> interconnect
>> + driver which controls the scaling of L3 caches on Qualcomm
>> SoCs.
>> +
>> config INTERCONNECT_QCOM_QCS404
>> tristate "Qualcomm QCS404 interconnect driver"
>> depends on INTERCONNECT_QCOM
>> diff --git a/drivers/interconnect/qcom/Makefile
>> b/drivers/interconnect/qcom/Makefile
>> index 9adf9e380545e..8d86d6515ffc9 100644
>> --- a/drivers/interconnect/qcom/Makefile
>> +++ b/drivers/interconnect/qcom/Makefile
>> @@ -1,10 +1,12 @@
>> # SPDX-License-Identifier: GPL-2.0
>>
>> +icc-osm-l3-objs := osm-l3.o
>> qnoc-msm8974-objs := msm8974.o
>> qnoc-qcs404-objs := qcs404.o
>> qnoc-sdm845-objs := sdm845.o
>> icc-smd-rpm-objs := smd-rpm.o
>>
>> +obj-$(CONFIG_INTERCONNECT_QCOM_OSM_L3) += icc-osm-l3.o
>> obj-$(CONFIG_INTERCONNECT_QCOM_MSM8974) += qnoc-msm8974.o
>> obj-$(CONFIG_INTERCONNECT_QCOM_QCS404) += qnoc-qcs404.o
>> obj-$(CONFIG_INTERCONNECT_QCOM_SDM845) += qnoc-sdm845.o
>> diff --git a/drivers/interconnect/qcom/osm-l3.c
>> b/drivers/interconnect/qcom/osm-l3.c
>> new file mode 100644
>> index 0000000000000..5e9f9ce02863b
>> --- /dev/null
>> +++ b/drivers/interconnect/qcom/osm-l3.c
>> @@ -0,0 +1,284 @@
>> +// SPDX-License-Identifier: GPL-2.0
>> +/*
>> + * Copyright (c) 2019, The Linux Foundation. All rights reserved.
>> + *
>> + */
>> +
>> +#include <dt-bindings/interconnect/qcom,osm-l3.h>
>> +#include <dt-bindings/interconnect/qcom,sdm845.h>
>> +#include <linux/bitfield.h>
>> +#include <linux/clk.h>
>> +#include <linux/interconnect-provider.h>
>> +#include <linux/io.h>
>> +#include <linux/kernel.h>
>> +#include <linux/module.h>
>> +#include <linux/of_device.h>
>> +#include <linux/of_platform.h>
>> +#include <linux/platform_device.h>
>> +
>> +#define LUT_MAX_ENTRIES 40U
>> +#define LUT_SRC GENMASK(31, 30)
>> +#define LUT_L_VAL GENMASK(7, 0)
>> +#define LUT_ROW_SIZE 32
>> +#define CLK_HW_DIV 2
>> +
>> +/* Register offsets */
>> +#define REG_ENABLE 0x0
>> +#define REG_FREQ_LUT 0x110
>> +#define REG_PERF_STATE 0x920
>> +
>> +#define OSM_L3_MAX_LINKS 1
>> +
>> +#define to_qcom_provider(_provider) \
>> + container_of(_provider, struct qcom_osm_l3_icc_provider,
>> provider)
>> +
>> +enum {
>> + SDM845_MASTER_OSM_L3_APPS = SLAVE_TCU + 1,
>> + SDM845_SLAVE_OSM_L3,
>> +};
>
> Should these just go in qcom,sdm845.h? Seems nice to have them all in
> one place, and then they can be accessed in the DT if needed.

yeah I can do that, by doing
this I can also get rid of the
SLAVE_TCU + 1 :)

>
>> +
>> +struct qcom_osm_l3_icc_provider {
>> + void __iomem *base;
>> + unsigned int max_state;
>> + unsigned long lut_tables[LUT_MAX_ENTRIES];
>> + struct icc_provider provider;
>> +};
>> +
>> +/**
>> + * struct qcom_icc_node - Qualcomm specific interconnect nodes
>> + * @name: the node name used in debugfs
>> + * @links: an array of nodes where we can go next while traversing
>> + * @id: a unique node identifier
>> + * @num_links: the total number of @links
>> + * @buswidth: width of the interconnect between a node and the bus
>> + */
>> +struct qcom_icc_node {
>> + const char *name;
>> + u16 links[OSM_L3_MAX_LINKS];
>> + u16 id;
>> + u16 num_links;
>> + u16 buswidth;
>> +};
>> +
>> +struct qcom_icc_desc {
>> + struct qcom_icc_node **nodes;
>> + size_t num_nodes;
>> +};
>> +
>> +#define DEFINE_QNODE(_name, _id, _buswidth, ...)
>> \
>> + static struct qcom_icc_node _name = {
>> \
>> + .name = #_name,
>> \
>> + .id = _id,
>> \
>> + .buswidth = _buswidth,
>> \
>> + .num_links = ARRAY_SIZE(((int[]){ __VA_ARGS__ })),
>> \
>> + .links = { __VA_ARGS__ },
>> \
>> + }
>> +
>> +DEFINE_QNODE(osm_apps_l3, SDM845_MASTER_OSM_L3_APPS, 16,
>> SDM845_SLAVE_OSM_L3);
>> +DEFINE_QNODE(osm_l3, SDM845_SLAVE_OSM_L3, 16);
>> +
>> +static struct qcom_icc_node *sdm845_osm_l3_nodes[] = {
>
> const?

unfortunately we can't ...

data->nodes[i] = node;
we setup links later ^^ with
the pointer.

>
>> + [MASTER_OSM_L3_APPS] = &osm_apps_l3,
>> + [SLAVE_OSM_L3] = &osm_l3,
>> +};
>> +
>> +static struct qcom_icc_desc sdm845_osm_l3 = {
>> + .nodes = sdm845_osm_l3_nodes,
>> + .num_nodes = ARRAY_SIZE(sdm845_osm_l3_nodes),
>> +};
>> +
>> +static int qcom_icc_aggregate(struct icc_node *node, u32 tag, u32
>> avg_bw,
>> + u32 peak_bw, u32 *agg_avg, u32
>> *agg_peak)
>> +{
>> + *agg_avg += avg_bw;
>> + *agg_peak = max_t(u32, *agg_peak, peak_bw);
>> +
>> + return 0;
>> +}
>
> Georgi, I wonder if it's a good idea to make a small collection of
> "std" aggregate functions in the interconnect core that a driver can
> just point to if it's doing something super standard like this (ie
> driver->aggregate = icc_std_aggregate;). This is probably fine as-is
> for now, but if we see a lot more copy/pastes of this function we
> should think about it.
>
>> +
>> +static int qcom_icc_set(struct icc_node *src, struct icc_node *dst)
>> +{
>> + struct qcom_osm_l3_icc_provider *qp;
>> + struct icc_provider *provider;
>> + struct qcom_icc_node *qn;
>> + struct icc_node *n;
>> + unsigned int index;
>> + u32 agg_peak = 0;
>> + u32 agg_avg = 0;
>> + u64 rate;
>> +
>> + qn = src->data;
>> + provider = src->provider;
>> + qp = to_qcom_provider(provider);
>> +
>> + list_for_each_entry(n, &provider->nodes, node_list)
>> + qcom_icc_aggregate(n, 0, n->avg_bw, n->peak_bw,
>> + &agg_avg, &agg_peak);
>> +
>> + rate = max(agg_avg, agg_peak);
>> + rate = icc_units_to_bps(rate);
>> + do_div(rate, qn->buswidth);
>> +
>> + for (index = 0; index < qp->max_state; index++) {
>
> If the rate is too high, you'll end up setting max_state into the
> register. That's probably bad, right? (Or maybe it's not because the
> table ends with the same value twice, but it seems like relying on an
> implementation detail). We could guard against that by only iterating
> to index < qp->max_state - 1.

yes, using max_state - 1 makes sense
here. Will change this in the next
re-spin.

>
>> + if (qp->lut_tables[index] >= rate)
>> + break;
>> + }
>> +
>> + writel_relaxed(index, qp->base + REG_PERF_STATE);
>> +
>> + return 0;
>> +}
>> +
>> +static int qcom_osm_l3_remove(struct platform_device *pdev)
>> +{
>> + struct qcom_osm_l3_icc_provider *qp =
>> platform_get_drvdata(pdev);
>> + struct icc_provider *provider = &qp->provider;
>> + struct icc_node *n;
>> +
>> + list_for_each_entry(n, &provider->nodes, node_list) {
>
> There was a comment on one of the other threads that we've been
> copy/pasting this snippet around and it's wrong because it doesn't use
> the _safe variant of the macro. So we end up destroying the list we're
> iterating over.
>
> Georgi, did you have a plan to refactor this, or should we just change
> this to be the _safe version?
>
>> + icc_node_del(n);
>> + icc_node_destroy(n->id);
>> + }
>> +
>> + return icc_provider_del(provider);
>> +}
>> +
>> +static int qcom_osm_l3_probe(struct platform_device *pdev)
>> +{
>> + u32 info, src, lval, i, prev_freq = 0, freq;
>> + static unsigned long hw_rate, xo_rate;
>> + struct qcom_osm_l3_icc_provider *qp;
>> + const struct qcom_icc_desc *desc;
>> + struct icc_onecell_data *data;
>> + struct icc_provider *provider;
>> + struct qcom_icc_node **qnodes;
>> + struct icc_node *node;
>> + size_t num_nodes;
>> + struct clk *clk;
>> + int ret;
>> +
>> + clk = clk_get(&pdev->dev, "xo");
>> + if (IS_ERR(clk))
>> + return PTR_ERR(clk);
>> +
>> + xo_rate = clk_get_rate(clk);
>> + clk_put(clk);
>> +
>> + clk = clk_get(&pdev->dev, "alternate");
>> + if (IS_ERR(clk))
>> + return PTR_ERR(clk);
>> +
>> + hw_rate = clk_get_rate(clk) / CLK_HW_DIV;
>
> It's a little weird there's a constant divide in there, though I guess
> it's in the cpufreq driver as well. I guess this is fine if it's
> likely to stay there (and the same) when this driver is generalized
> for other SoCs.

yeah I don't see this changing
on sc7180 so I'll leave this
as is.

>
>> + clk_put(clk);
>> +
>> + qp = devm_kzalloc(&pdev->dev, sizeof(*qp), GFP_KERNEL);
>> + if (!qp)
>> + return -ENOMEM;
>> +
>> + qp->base = devm_platform_ioremap_resource(pdev, 0);
>> + if (IS_ERR(qp->base))
>> + return PTR_ERR(qp->base);
>> +
>> + /* HW should be in enabled state to proceed */
>> + if (!(readl_relaxed(qp->base + REG_ENABLE) & 0x1)) {
>> + dev_err(&pdev->dev, "error hardware not enabled\n");
>> + return -ENODEV;
>> + }
>> +
>> + for (i = 0; i < LUT_MAX_ENTRIES; i++) {
>> + info = readl_relaxed(qp->base + REG_FREQ_LUT +
>> + i * LUT_ROW_SIZE);
>> + src = FIELD_GET(LUT_SRC, info);
>> + lval = FIELD_GET(LUT_L_VAL, info);
>> + if (src)
>> + freq = xo_rate * lval;
>> + else
>> + freq = hw_rate;
>> +
>> + /*
>> + * Two of the same frequencies with the same core
>> counts means
>
> "core counts" seems like a copied comment that doesn't apply.

yes we don't use the core_cnt
field so will update the comment.

>
> But you only look at freq and not core count, is that really
> equivalent to the table's boundary condition? Or do you need to be
> comparing info == info_prev?

no we can get by comparing
current freq with prev freq
on OSM L3.

>
>> + * end of table
>> + */
>> + if (i > 0 && prev_freq == freq)
>> + break;
>> +
>> + qp->lut_tables[i] = freq;
>> + prev_freq = freq;
>> + }
>> + qp->max_state = i;
>
> Should we error out or complain if there are too few entries, or if
> the table is not in increasing order?

OSM does make sure of the
increasing order and correct
number of freq entries if the
REG_ENABLE is set. However I
don't really mind adding the
increasing order check but we
can't really detect too few
entries since the number can
vary across SKUs.

>
>> +
>> + desc = of_device_get_match_data(&pdev->dev);
>> + if (!desc)
>> + return -EINVAL;
>> +
>> + qnodes = desc->nodes;
>> + num_nodes = desc->num_nodes;
>> +
>> + data = devm_kcalloc(&pdev->dev, num_nodes, sizeof(*node),
>> GFP_KERNEL);
>> + if (!data)
>> + return -ENOMEM;
>> +
>> + provider = &qp->provider;
>> + provider->dev = &pdev->dev;
>> + provider->set = qcom_icc_set;
>> + provider->aggregate = qcom_icc_aggregate;
>> + provider->xlate = of_icc_xlate_onecell;
>> + INIT_LIST_HEAD(&provider->nodes);
>> + provider->data = data;
>> +
>> + ret = icc_provider_add(provider);
>> + if (ret) {
>> + dev_err(&pdev->dev, "error adding interconnect
>> provider\n");
>> + return ret;
>> + }
>> +
>> + for (i = 0; i < num_nodes; i++) {
>> + size_t j;
>> +
>> + node = icc_node_create(qnodes[i]->id);
>> + if (IS_ERR(node)) {
>> + ret = PTR_ERR(node);
>> + goto err;
>> + }
>> +
>> + node->name = qnodes[i]->name;
>> + node->data = qnodes[i];
>> + icc_node_add(node, provider);
>> +
>> + dev_dbg(&pdev->dev, "registered node %p %s %d\n",
>> node,
>> + qnodes[i]->name, node->id);
>> +
>> + /* populate links */
>
> Not a super useful comment.

lol will remove it

>
>
>> + for (j = 0; j < qnodes[i]->num_links; j++)
>> + icc_link_create(node, qnodes[i]->links[j]);
>> +
>> + data->nodes[i] = node;
>> + }
>> + data->num_nodes = num_nodes;
>> +
>> + platform_set_drvdata(pdev, qp);
>> +
>> + return ret;
>> +err:
>> + qcom_osm_l3_remove(pdev);
>> + return ret;
>> +}
>> +
>> +static const struct of_device_id osm_l3_of_match[] = {
>> + { .compatible = "qcom,sdm845-osm-l3", .data = &sdm845_osm_l3
>> },
>> + { },
>> +};
>> +MODULE_DEVICE_TABLE(of, osm_l3_of_match);
>> +
>> +static struct platform_driver osm_l3_driver = {
>> + .probe = qcom_osm_l3_probe,
>> + .remove = qcom_osm_l3_remove,
>> + .driver = {
>> + .name = "osm-l3",
>> + .of_match_table = osm_l3_of_match,
>> + },
>> +};
>> +module_platform_driver(osm_l3_driver);
>> +
>> +MODULE_DESCRIPTION("Qualcomm OSM L3 interconnect driver");
>> +MODULE_LICENSE("GPL v2");
>> --
>> The Qualcomm Innovation Center, Inc. is a member of the Code Aurora
>> Forum,
>> a Linux Foundation Collaborative Project
>>

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