Re: [PATCH v4 05/13] peci: Add peci-aspeed controller driver

["Winiarska, Iwona" <iwona.winiarska@intel.com>]

On Mon, 2021-12-06 at 05:27 +0000, Billy Tsai wrote:
> Hi,
> 
> After reviewing the patch, I have some suggestions for you. Please see the
> reply inline.
> 
> On 2021/11/23, 10:11 PM, "openbmc on behalf of Iwona Winiarska"
> <openbmc-bounces+billy_tsai=aspeedtech.com@lists.ozlabs.org on behalf of
> iwona.winiarska@intel.com> wrote:
> 
>     >   From: Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>
> Add the define for the bus frequency
>         #define ASPEED_PECI_BUS_FREQUENCY_MIN           2000
>         #define ASPEED_PECI_BUS_FREQUENCY_DEFAULT       2000
>         #define ASPEED_PECI_BUS_FREQUENCY_MAX           1000000
> 
>    >   +struct aspeed_peci {
>     >   +       struct peci_controller *controller;
>     >   +       struct device *dev;
>     >   +       void __iomem *base;
>     >   +       struct clk *clk;
>     >   +       struct reset_control *rst;
>     >   +       int irq;
>     >   +       spinlock_t lock; /* to sync completion status handling */
>     >   +       struct completion xfer_complete;
>     >   +       u32 status;
>     >   +       u32 cmd_timeout_ms;
>     >   +       u32 msg_timing;
>     >   +       u32 addr_timing;
>     >   +       u32 rd_sampling_point;
>     >   +       u32 clk_div;
> 
> Add the paremeter to store the bus_freq from the dts property
>         u32 bus_freq;
> 
>     >   +};
>     >   +
>     >   +static void aspeed_peci_init_regs(struct aspeed_peci *priv)
>     >   +{
>     >   +       u32 val;
>     >   +
>     >   +       val = FIELD_PREP(ASPEED_PECI_CTRL_CLK_DIV_MASK,
> ASPEED_PECI_CLK_DIV_DEFAULT);
>     >   +       val |= ASPEED_PECI_CTRL_PECI_CLK_EN;
>     >   +       writel(val, priv->base + ASPEED_PECI_CTRL);
>     >   +       /*
>     >   +        * Timing negotiation period setting.
>     >   +        * The unit of the programmed value is 4 times of PECI clock
> period.
>     >   +        */
>     >   +       val = FIELD_PREP(ASPEED_PECI_T_NEGO_MSG_MASK, priv-
> >msg_timing);
>     >   +       val |= FIELD_PREP(ASPEED_PECI_T_NEGO_ADDR_MASK, priv-
> >addr_timing);
>     >   +       writel(val, priv->base + ASPEED_PECI_TIMING_NEGOTIATION);
>     >   +
>     >   +       /* Clear interrupts */
>     >   +       val = readl(priv->base + ASPEED_PECI_INT_STS) |
> ASPEED_PECI_INT_MASK;
>     >   +       writel(val, priv->base + ASPEED_PECI_INT_STS);
>     >   +
>     >   +       /* Set timing negotiation mode and enable interrupts */
>     >   +       val = FIELD_PREP(ASPEED_PECI_TIMING_NEGO_SEL_MASK,
> ASPEED_PECI_1ST_BIT_OF_ADDR_NEGO);
>     >   +       val |= ASPEED_PECI_INT_MASK;
>     >   +       writel(val, priv->base + ASPEED_PECI_INT_CTRL);
>     >   +
>     >   +       val = FIELD_PREP(ASPEED_PECI_CTRL_SAMPLING_MASK, priv-
> >rd_sampling_point);
>     >   +       val |= FIELD_PREP(ASPEED_PECI_CTRL_CLK_DIV_MASK, priv-
> >clk_div);
>     >   +       val |= ASPEED_PECI_CTRL_PECI_EN;
>     >   +       val |= ASPEED_PECI_CTRL_PECI_CLK_EN;
>     >   +       writel(val, priv->base + ASPEED_PECI_CTRL);
>     >   +}
>     >   +
>     >   +static inline int aspeed_peci_check_idle(struct aspeed_peci *priv)
>     >   +{
>     >   +       u32 cmd_sts = readl(priv->base + ASPEED_PECI_CMD);
>     >   +
>     >   +       if (FIELD_GET(ASPEED_PECI_CMD_STS_MASK, cmd_sts) ==
> ASPEED_PECI_CMD_STS_ADDR_T_NEGO)
>     >   +               aspeed_peci_init_regs(priv);
> 
> As long as the state is not idle, the controller need to reinitialize the PECI
> register for solving the PECI controller hang.
> Before ast2600A3, the controller should assert/de-assert the reset for solving
> the hang issue.
> For backward compatible, I suggest to add the reset assert/de-assert in this
> place.
>         if (FIELD_GET(ASPEED_PECI_CMD_STS_MASK, cmd_sts)) {
>                         reset_control_assert(priv->rst);
>                         reset_control_deassert(priv->rst);
>                         aspeed_peci_init_regs(priv);
>         }

Ack.

> 

(...)

>     >   +static void aspeed_peci_property_setup(struct aspeed_peci *priv)
>     >   +{
>     >   +       aspeed_peci_property_sanitize(priv->dev, "aspeed,clock-
> divider",
>     >   +                                     0, ASPEED_PECI_CLK_DIV_MAX,
>     >   +                                     ASPEED_PECI_CLK_DIV_DEFAULT,
> &priv->clk_div);
>     >   +       aspeed_peci_property_sanitize(priv->dev, "aspeed,msg-timing",
>     >   +                                     0, ASPEED_PECI_MSG_TIMING_MAX,
>     >   +                                     ASPEED_PECI_MSG_TIMING_DEFAULT,
> &priv->msg_timing);
>     >   +       aspeed_peci_property_sanitize(priv->dev, "aspeed,addr-timing",
>     >   +                                     0, ASPEED_PECI_ADDR_TIMING_MAX,
>     >   +                                     ASPEED_PECI_ADDR_TIMING_DEFAULT,
> &priv->addr_timing);
> 
> Use the bus-frequency to replace the property above:
>         aspeed_peci_property_sanitize(priv->dev, "bus-frequency",
>                                 ASPEED_PECI_BUS_FREQUENCY_MIN,
> ASPEED_PECI_BUS_FREQUENCY_MAX,
>                                 ASPEED_PECI_BUS_FREQUENCY_DEFAULT, &priv-
> >bus_freq);
> 
>     >   +       aspeed_peci_property_sanitize(priv->dev, "aspeed,rd-sampling-
> point",
>     >   +                                     0,
> ASPEED_PECI_RD_SAMPLING_POINT_MAX,
>     >   +                                    
> ASPEED_PECI_RD_SAMPLING_POINT_DEFAULT,
>     >   +                                     &priv->rd_sampling_point);
>     >   +       aspeed_peci_property_sanitize(priv->dev, "cmd-timeout-ms",
>     >   +                                     1,
> ASPEED_PECI_CMD_TIMEOUT_MS_MAX,
>     >   +                                    
> ASPEED_PECI_CMD_TIMEOUT_MS_DEFAULT, &priv->cmd_timeout_ms);
>     >   +}
> Add the function of automatically calculating the settings to adapt to the bus
> frequency.

If we want to go with exposing "bus-frequency", instead of hardware properties,
I don't think we should opencode it in this way.
Rather, we should expose it as a clock, passing "clock-frequency" property via
DTS and exposing it using struct clk_hw.
We would then just call clock API (clk_round_rate / clk_set_rate etc),
presenting this as what it actually is (a "custom" clock divider).

Thanks
-Iwona

>         static void aspeed_peci_bus_freq_setup(struct aspeed_peci *priv)
>         {
>                 unsigned long src_clk_rate;
>                 int delta_value, delta_tmp, clk_divisor, clk_divisor_tmp;
>                 u32 msg_timing, clk_div;
> 
>                 src_clk_rate = clk_get_rate(priv->clk);
> 
>                 /*
>                  * PECI bus freq  = (source clk rate) / (4 *
> (PECI04[15:8]*4+1) * (1 << PECI00[10:8]))
>                  * (1 << PECI00[10:8]) * (PECI04[15:8]*4+1) = (source clk
> rate) / (4 * PECI bus freq )
>                  */
>                 clk_divisor = src_clk_rate / (4 * priv->bus_freq);
>                 delta_value = clk_divisor;
>                 /* Find the closest divisor for bus-frequency */
>                 for (msg_timing = 1; msg_timing <= 255; msg_timing++)
>                         for (clk_div = 0; clk_div < 7;
>                                 clk_div++) {
>                                 clk_divisor_tmp = (1 << clk_div) *
>                                                 (msg_timing * 4 + 1);
>                                 delta_tmp = abs(clk_divisor -
> clk_divisor_tmp);
>                                 if (delta_tmp < delta_value) {
>                                         delta_value = delta_tmp;
>                                         priv->msg_timing = msg_timing;
>                                         priv->addr_timing = priv->msg_timing;
>                                         priv->clk_div = clk_div;
>                                 }
>                         }
>         }
> 
>     >   +
>     >   +static struct peci_controller_ops aspeed_ops = {
>     >   +       .xfer = aspeed_peci_xfer,
>     >   +};
>     >   +
>     >   +static void aspeed_peci_reset_control_release(void *data)
>     >   +{
>     >   +       reset_control_assert(data);
>     >   +}
>     >   +
>     >   +static int devm_aspeed_peci_reset_control_deassert(struct device
> *dev, struct reset_control *rst)
>     >   +{
>     >   +       int ret;
>     >   +
>     >   +       ret = reset_control_deassert(rst);
>     >   +       if (ret)
>     >   +               return ret;
>     >   +
>     >   +       return devm_add_action_or_reset(dev,
> aspeed_peci_reset_control_release, rst);
>     >   +}
>     >   +
>     >   +static void aspeed_peci_clk_release(void *data)
>     >   +{
>     >   +       clk_disable_unprepare(data);
>     >   +}
>     >   +
>     >   +static int devm_aspeed_peci_clk_enable(struct device *dev, struct clk
> *clk)
>     >   +{
>     >   +       int ret;
>     >   +
>     >   +       ret = clk_prepare_enable(clk);
>     >   +       if (ret)
>     >   +               return ret;
>     >   +
>     >   +       return devm_add_action_or_reset(dev, aspeed_peci_clk_release,
> clk);
>     >   +}
>     >   +
>     >   +static int aspeed_peci_probe(struct platform_device *pdev)
>     >   +{
>     >   +       struct peci_controller *controller;
>     >   +       struct aspeed_peci *priv;
>     >   +       int ret;
>     >   +
>     >   +       priv = devm_kzalloc(&pdev->dev, sizeof(*priv), GFP_KERNEL);
>     >   +       if (!priv)
>     >   +               return -ENOMEM;
>     >   +
>     >   +       priv->dev = &pdev->dev;
>     >   +       dev_set_drvdata(priv->dev, priv);
>     >   +
>     >   +       priv->base = devm_platform_ioremap_resource(pdev, 0);
>     >   +       if (IS_ERR(priv->base))
>     >   +               return PTR_ERR(priv->base);
>     >   +
>     >   +       priv->irq = platform_get_irq(pdev, 0);
>     >   +       if (!priv->irq)
>     >   +               return priv->irq;
>     >   +
>     >   +       ret = devm_request_irq(&pdev->dev, priv->irq,
> aspeed_peci_irq_handler,
>     >   +                              0, "peci-aspeed", priv);
>     >   +       if (ret)
>     >   +               return ret;
>     >   +
>     >   +       init_completion(&priv->xfer_complete);
>     >   +       spin_lock_init(&priv->lock);
>     >   +
>     >   +       priv->rst = devm_reset_control_get(&pdev->dev, NULL);
>     >   +       if (IS_ERR(priv->rst))
>     >   +               return dev_err_probe(priv->dev, PTR_ERR(priv->rst),
>     >   +                                    "failed to get reset control\n");
>     >   +
>     >   +       ret = devm_aspeed_peci_reset_control_deassert(priv->dev, priv-
> >rst);
>     >   +       if (ret)
>     >   +               return dev_err_probe(priv->dev, ret, "cannot deassert
> reset control\n");
>     >   +
>     >   +       priv->clk = devm_clk_get(priv->dev, NULL);
>     >   +       if (IS_ERR(priv->clk))
>     >   +               return dev_err_probe(priv->dev, PTR_ERR(priv->clk),
> "failed to get clk\n");
>     >   +
>     >   +       ret = devm_aspeed_peci_clk_enable(priv->dev, priv->clk);
>     >   +       if (ret)
>     >   +               return dev_err_probe(priv->dev, ret, "failed to enable
> clock\n");
>     >   +
>     >   +       aspeed_peci_property_setup(priv);
> 
>         aspeed_peci_bus_freq_setup(priv);
> 
>     >   +
>     >   +       aspeed_peci_init_regs(priv);
>     >   +
>     >   +       controller = devm_peci_controller_add(priv->dev, &aspeed_ops);
>     >   +       if (IS_ERR(controller))
>     >   +               return dev_err_probe(priv->dev, PTR_ERR(controller),
>     >   +                                    "failed to add aspeed peci
> controller\n");
>     >   +
>     >   +       priv->controller = controller;
>     >   +
>     >   +       return 0;
>     >   +}
>     >   +
>     >   +static const struct of_device_id aspeed_peci_of_table[] = {
>     >   +       { .compatible = "aspeed,ast2400-peci", },
>     >   +       { .compatible = "aspeed,ast2500-peci", },
>     >   +       { .compatible = "aspeed,ast2600-peci", },
>     >   +       { }
>     >   +};
>     >   +MODULE_DEVICE_TABLE(of, aspeed_peci_of_table);
>     >   +
>     >   +static struct platform_driver aspeed_peci_driver = {
>     >   +       .probe  = aspeed_peci_probe,
>     >   +       .driver = {
>     >   +               .name           = "peci-aspeed",
>     >   +               .of_match_table = aspeed_peci_of_table,
>     >   +       },
>     >   +};
>     >   +module_platform_driver(aspeed_peci_driver);
>     >   +
>     >   +MODULE_AUTHOR("Ryan Chen <ryan_chen@aspeedtech.com>");
>     >   +MODULE_AUTHOR("Jae Hyun Yoo <jae.hyun.yoo@linux.intel.com>");
>     >   +MODULE_DESCRIPTION("ASPEED PECI driver");
>     >   +MODULE_LICENSE("GPL");
>     >   +MODULE_IMPORT_NS(PECI);
>     >   -- 
>     >   2.31.1
> 
> 
> 

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