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Message-ID: <670e4bd2c9d8dc91d1c9fca2b050915942b2a9b2.camel@intel.com>
Date: Tue, 7 Dec 2021 18:09:36 +0000
From: "Winiarska, Iwona" <iwona.winiarska@...el.com>
To: "billy_tsai@...eedtech.com" <billy_tsai@...eedtech.com>,
"gregkh@...uxfoundation.org" <gregkh@...uxfoundation.org>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"openbmc@...ts.ozlabs.org" <openbmc@...ts.ozlabs.org>
CC: "corbet@....net" <corbet@....net>,
"jae.hyun.yoo@...ux.intel.com" <jae.hyun.yoo@...ux.intel.com>,
"linux-hwmon@...r.kernel.org" <linux-hwmon@...r.kernel.org>,
"andrew@...id.au" <andrew@...id.au>,
"Hansen, Dave" <dave.hansen@...el.com>,
"Luck, Tony" <tony.luck@...el.com>,
"jdelvare@...e.com" <jdelvare@...e.com>,
"olof@...om.net" <olof@...om.net>,
"rdunlap@...radead.org" <rdunlap@...radead.org>,
"devicetree@...r.kernel.org" <devicetree@...r.kernel.org>,
"linux-aspeed@...ts.ozlabs.org" <linux-aspeed@...ts.ozlabs.org>,
"linux@...ck-us.net" <linux@...ck-us.net>,
"arnd@...db.de" <arnd@...db.de>,
"linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>,
"robh+dt@...nel.org" <robh+dt@...nel.org>,
"zweiss@...inix.com" <zweiss@...inix.com>,
"bp@...en8.de" <bp@...en8.de>,
"linux-arm-kernel@...ts.infradead.org"
<linux-arm-kernel@...ts.infradead.org>,
"pierre-louis.bossart@...ux.intel.com"
<pierre-louis.bossart@...ux.intel.com>,
"andriy.shevchenko@...ux.intel.com"
<andriy.shevchenko@...ux.intel.com>,
"Williams, Dan J" <dan.j.williams@...el.com>
Subject: Re: [PATCH v4 05/13] peci: Add peci-aspeed controller driver
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@...ts.ozlabs.org on behalf of
> iwona.winiarska@...el.com> wrote:
>
> > From: Jae Hyun Yoo <jae.hyun.yoo@...ux.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@...eedtech.com>");
> > +MODULE_AUTHOR("Jae Hyun Yoo <jae.hyun.yoo@...ux.intel.com>");
> > +MODULE_DESCRIPTION("ASPEED PECI driver");
> > +MODULE_LICENSE("GPL");
> > +MODULE_IMPORT_NS(PECI);
> > --
> > 2.31.1
>
>
>
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