Re: [PATCH v9 08/13] drivers: memory: add DMC driver for Exynos5422

[Krzysztof Kozlowski]

On Fri, 7 Jun 2019 at 16:35, Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx> wrote:
>
> This patch adds driver for Exynos5422 Dynamic Memory Controller.
> The driver provides support for dynamic frequency and voltage scaling for
> DMC and DRAM. It supports changing timings of DRAM running with different
> frequency. There is also an algorithm to calculate timigns based on
> memory description provided in DT.
> The patch also contains needed MAINTAINERS file update.
>
> Signed-off-by: Lukasz Luba <l.luba@xxxxxxxxxxxxxxxxxxx>
> ---
>  MAINTAINERS                             |    8 +
>  drivers/memory/samsung/Kconfig          |   17 +
>  drivers/memory/samsung/Makefile         |    1 +
>  drivers/memory/samsung/exynos5422-dmc.c | 1261 +++++++++++++++++++++++
>  4 files changed, 1287 insertions(+)
>  create mode 100644 drivers/memory/samsung/exynos5422-dmc.c

(...)

> +
> +/**
> + * exynos5_performance_counters_init() - Initializes performance DMC's counters
> + * @dmc:       DMC for which it does the setup
> + *
> + * Initialization of performance counters in DMC for estimating usage.
> + * The counter's values are used for calculation of a memory bandwidth and based
> + * on that the governor changes the frequency.
> + * The counters are not used when the governor is GOVERNOR_USERSPACE.
> + */
> +static int exynos5_performance_counters_init(struct exynos5_dmc *dmc)
> +{
> +       int counters_size;
> +       int ret, i;
> +
> +       dmc->num_counters = devfreq_event_get_edev_count(dmc->dev);
> +       if (dmc->num_counters < 0) {
> +               dev_err(dmc->dev, "could not get devfreq-event counters\n");
> +               return dmc->num_counters;
> +       }
> +
> +       counters_size = sizeof(struct devfreq_event_dev) * dmc->num_counters;
> +       dmc->counter = devm_kzalloc(dmc->dev, counters_size, GFP_KERNEL);
> +       if (!dmc->counter)
> +               return -ENOMEM;
> +
> +       for (i = 0; i < dmc->num_counters; i++) {
> +               dmc->counter[i] =
> +                       devfreq_event_get_edev_by_phandle(dmc->dev, i);
> +               if (IS_ERR_OR_NULL(dmc->counter[i]))
> +                       return -EPROBE_DEFER;
> +       }
> +
> +       ret = exynos5_counters_enable_edev(dmc);
> +       if (ret < 0) {
> +               dev_err(dmc->dev, "could not enable event counter\n");
> +               return ret;
> +       }
> +
> +       ret = exynos5_counters_set_event(dmc);
> +       if (ret < 0) {
> +               dev_err(dmc->dev, "counld not set event counter\n");

Missing cleanup - edev counters disable.

> +               return ret;
> +       }
> +
> +       return 0;
> +}
> +
> +/**
> + * exynos5_dmc_set_pause_on_switching() - Controls a pause feature in DMC
> + * @dmc:       device which is used for changing this feature
> + * @set:       a boolean state passing enable/disable request
> + *
> + * There is a need of pausing DREX DMC when divider or MUX in clock tree
> + * changes its configuration. In such situation access to the memory is blocked
> + * in DMC automatically. This feature is used when clock frequency change
> + * request appears and touches clock tree.
> + */
> +static inline int exynos5_dmc_set_pause_on_switching(struct exynos5_dmc *dmc)
> +{
> +       unsigned int val;
> +       int ret;
> +
> +       ret = regmap_read(dmc->clk_regmap, CDREX_PAUSE, &val);
> +       if (ret)
> +               return ret;
> +
> +       val |= 1UL;
> +       regmap_write(dmc->clk_regmap, CDREX_PAUSE, val);
> +
> +       return 0;
> +}
> +
> +/**
> + * exynos5_dmc_probe() - Probe function for the DMC driver
> + * @pdev:      platform device for which the driver is going to be initialized
> + *
> + * Initialize basic components: clocks, regulators, performance counters, etc.
> + * Read out product version and based on the information setup
> + * internal structures for the controller (frequency and voltage) and for DRAM
> + * memory parameters: timings for each operating frequency.
> + * Register new devfreq device for controlling DVFS of the DMC.
> + */
> +static int exynos5_dmc_probe(struct platform_device *pdev)
> +{
> +       int ret = 0;
> +       struct device *dev = &pdev->dev;
> +       struct device_node *np = dev->of_node;
> +       struct exynos5_dmc *dmc;
> +       struct resource *res;
> +
> +       dmc = devm_kzalloc(dev, sizeof(*dmc), GFP_KERNEL);
> +       if (!dmc)
> +               return -ENOMEM;
> +
> +       mutex_init(&dmc->lock);
> +
> +       dmc->dev = dev;
> +       platform_set_drvdata(pdev, dmc);
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
> +       dmc->base_drexi0 = devm_ioremap_resource(dev, res);
> +       if (IS_ERR(dmc->base_drexi0))
> +               return PTR_ERR(dmc->base_drexi0);
> +
> +       res = platform_get_resource(pdev, IORESOURCE_MEM, 1);
> +       dmc->base_drexi1 = devm_ioremap_resource(dev, res);
> +       if (IS_ERR(dmc->base_drexi1))
> +               return PTR_ERR(dmc->base_drexi1);
> +
> +       dmc->clk_regmap = syscon_regmap_lookup_by_phandle(np,
> +                               "samsung,syscon-clk");
> +       if (IS_ERR(dmc->clk_regmap))
> +               return PTR_ERR(dmc->clk_regmap);
> +
> +       ret = exynos5_init_freq_table(dmc, &exynos5_dmc_df_profile);
> +       if (ret) {
> +               dev_warn(dev, "couldn't initialize frequency settings\n");
> +               return ret;
> +       }
> +
> +       dmc->vdd_mif = devm_regulator_get(dev, "vdd");
> +       if (IS_ERR(dmc->vdd_mif)) {
> +               ret = PTR_ERR(dmc->vdd_mif);
> +               return ret;
> +       }
> +
> +       ret = exynos5_dmc_init_clks(dmc);
> +       if (ret)
> +               return ret;
> +
> +       ret = of_get_dram_timings(dmc);
> +       if (ret) {
> +               dev_warn(dev, "couldn't initialize timings settings\n");

goto remove_clocks;

> +               return ret;
> +       }
> +
> +       ret = exynos5_performance_counters_init(dmc);
> +       if (ret) {
> +               dev_warn(dev, "couldn't probe performance counters\n");
> +               goto remove_clocks;
> +       }
> +
> +       ret = exynos5_dmc_set_pause_on_switching(dmc);
> +       if (ret) {
> +               dev_warn(dev, "couldn't get access to PAUSE register\n");
> +               goto remove_clocks;

goto err_devfreq_add;

Best regards,
Krzysztof

> +       }
> +
> +       /*
> +        * Setup default thresholds for the devfreq governor.
> +        * The values are chosen based on experiments.
> +        */
> +       dmc->gov_data.upthreshold = 30;
> +       dmc->gov_data.downdifferential = 5;
> +
> +       dmc->df = devm_devfreq_add_device(dev, &exynos5_dmc_df_profile,
> +                                         DEVFREQ_GOV_USERSPACE,
> +                                         &dmc->gov_data);
> +
> +       if (IS_ERR(dmc->df)) {
> +               ret = PTR_ERR(dmc->df);
> +               goto err_devfreq_add;
> +       }
> +
> +       dev_info(dev, "DMC initialized\n");
> +
> +       return 0;
> +
> +err_devfreq_add:
> +       exynos5_counters_disable_edev(dmc);
> +remove_clocks:
> +       clk_disable_unprepare(dmc->mout_bpll);
> +       clk_disable_unprepare(dmc->fout_bpll);
> +
> +       return ret;
> +}
> +
>