Re: [PATCH v3 2/2] leds: sun50i-r329: New driver for the R329/D1 LED controller

[Samuel Holland]

Hi Maxime,

On 11/19/21 2:28 AM, Maxime Ripard wrote:
> Hi,
> 
> On Thu, Nov 18, 2021 at 11:40:43PM -0600, Samuel Holland wrote:
>> +static const struct sun50i_r329_ledc_timing sun50i_r329_ledc_default_timing = {
>> +	.t0h_ns = 336,
>> +	.t0l_ns = 840,
>> +	.t1h_ns = 882,
>> +	.t1l_ns = 294,
>> +	.treset_ns = 300000,
>> +};
> 
> This should be mentioned in the binding as well (using the default keyword)

Ok, I'll do this for v4.

>> +static int sun50i_r329_ledc_parse_timing(const struct device_node *np,
>> +					 struct sun50i_r329_ledc *priv)
>> +{
>> +	struct sun50i_r329_ledc_timing *timing = &priv->timing;
>> +
>> +	*timing = sun50i_r329_ledc_default_timing;
>> +
>> +	of_property_read_u32(np, "allwinner,t0h-ns", &timing->t0h_ns);
>> +	of_property_read_u32(np, "allwinner,t0l-ns", &timing->t0l_ns);
>> +	of_property_read_u32(np, "allwinner,t1h-ns", &timing->t1h_ns);
>> +	of_property_read_u32(np, "allwinner,t1l-ns", &timing->t1l_ns);
>> +	of_property_read_u32(np, "allwinner,treset-ns", &timing->treset_ns);
>> +
>> +	return 0;
>> +}
>> +
>> +static void sun50i_r329_ledc_set_timing(struct sun50i_r329_ledc *priv)
>> +{
>> +	const struct sun50i_r329_ledc_timing *timing = &priv->timing;
>> +	unsigned long mod_freq = clk_get_rate(priv->mod_clk);
>> +	u32 cycle_ns = NSEC_PER_SEC / mod_freq;
>> +	u32 val;
>> +
>> +	val = (timing->t1h_ns / cycle_ns) << 21 |
>> +	      (timing->t1l_ns / cycle_ns) << 16 |
>> +	      (timing->t0h_ns / cycle_ns) <<  6 |
>> +	      (timing->t0l_ns / cycle_ns);
>> +	writel(val, priv->base + LEDC_T01_TIMING_CTRL_REG);
>> +
>> +	val = (timing->treset_ns / cycle_ns) << 16 |
>> +	      (priv->num_leds - 1);
>> +	writel(val, priv->base + LEDC_RESET_TIMING_CTRL_REG);
>> +}
>> +
>> +static int sun50i_r329_ledc_resume(struct device *dev)
>> +{
>> +	struct sun50i_r329_ledc *priv = dev_get_drvdata(dev);
>> +	u32 val;
>> +	int ret;
>> +
>> +	ret = reset_control_deassert(priv->reset);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = clk_prepare_enable(priv->bus_clk);
>> +	if (ret)
>> +		goto err_assert_reset;
>> +
>> +	ret = clk_prepare_enable(priv->mod_clk);
>> +	if (ret)
>> +		goto err_disable_bus_clk;
>> +
>> +	sun50i_r329_ledc_set_format(priv);
>> +	sun50i_r329_ledc_set_timing(priv);
>> +
>> +	/* The trigger level must be at least the burst length. */
>> +	val = readl(priv->base + LEDC_DMA_CTRL_REG);
>> +	val &= ~LEDC_DMA_CTRL_REG_FIFO_TRIG_LEVEL;
>> +	val |= LEDC_FIFO_DEPTH / 2;
>> +	writel(val, priv->base + LEDC_DMA_CTRL_REG);
>> +
>> +	val = LEDC_INT_CTRL_REG_GLOBAL_INT_EN |
>> +	      LEDC_INT_CTRL_REG_TRANS_FINISH_INT_EN;
>> +	writel(val, priv->base + LEDC_INT_CTRL_REG);
>> +
>> +	return 0;
>> +
>> +err_disable_bus_clk:
>> +	clk_disable_unprepare(priv->bus_clk);
>> +err_assert_reset:
>> +	reset_control_assert(priv->reset);
>> +
>> +	return ret;
>> +}
>> +
>> +static int sun50i_r329_ledc_suspend(struct device *dev)
>> +{
>> +	struct sun50i_r329_ledc *priv = dev_get_drvdata(dev);
>> +
>> +	clk_disable_unprepare(priv->mod_clk);
>> +	clk_disable_unprepare(priv->bus_clk);
>> +	reset_control_assert(priv->reset);
>> +
>> +	return 0;
>> +}
>> +
>> +static void sun50i_r329_ledc_dma_cleanup(void *data)
>> +{
>> +	struct sun50i_r329_ledc *priv = data;
>> +	struct device *dma_dev = dmaengine_get_dma_device(priv->dma_chan);
>> +
>> +	if (priv->buffer)
>> +		dma_free_wc(dma_dev, LEDS_TO_BYTES(priv->num_leds),
>> +			    priv->buffer, priv->dma_handle);
>> +	dma_release_channel(priv->dma_chan);
>> +}
>> +
>> +static int sun50i_r329_ledc_probe(struct platform_device *pdev)
>> +{
>> +	const struct device_node *np = pdev->dev.of_node;
>> +	struct dma_slave_config dma_cfg = {};
>> +	struct led_init_data init_data = {};
>> +	struct device *dev = &pdev->dev;
>> +	struct device_node *child;
>> +	struct sun50i_r329_ledc *priv;
>> +	struct resource *mem;
>> +	int count, irq, ret;
>> +
>> +	count = of_get_available_child_count(np);
>> +	if (!count)
>> +		return -ENODEV;
>> +	if (count > LEDC_MAX_LEDS) {
>> +		dev_err(dev, "Too many LEDs! (max is %d)\n", LEDC_MAX_LEDS);
>> +		return -EINVAL;
>> +	}
>> +
>> +	priv = devm_kzalloc(dev, struct_size(priv, leds, count), GFP_KERNEL);
>> +	if (!priv)
>> +		return -ENOMEM;
>> +
>> +	priv->dev = dev;
>> +	priv->num_leds = count;
>> +	spin_lock_init(&priv->lock);
>> +	dev_set_drvdata(dev, priv);
>> +
>> +	ret = sun50i_r329_ledc_parse_format(np, priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = sun50i_r329_ledc_parse_timing(np, priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	priv->base = devm_platform_get_and_ioremap_resource(pdev, 0, &mem);
>> +	if (IS_ERR(priv->base))
>> +		return PTR_ERR(priv->base);
>> +
>> +	priv->bus_clk = devm_clk_get(dev, "bus");
>> +	if (IS_ERR(priv->bus_clk))
>> +		return PTR_ERR(priv->bus_clk);
>> +
>> +	priv->mod_clk = devm_clk_get(dev, "mod");
>> +	if (IS_ERR(priv->mod_clk))
>> +		return PTR_ERR(priv->mod_clk);
>> +
>> +	priv->reset = devm_reset_control_get_exclusive(dev, NULL);
>> +	if (IS_ERR(priv->reset))
>> +		return PTR_ERR(priv->reset);
>> +
>> +	priv->dma_chan = dma_request_chan(dev, "tx");
>> +	if (IS_ERR(priv->dma_chan))
>> +		return PTR_ERR(priv->dma_chan);
>> +
>> +	ret = devm_add_action_or_reset(dev, sun50i_r329_ledc_dma_cleanup, priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	dma_cfg.dst_addr	= mem->start + LEDC_DATA_REG;
>> +	dma_cfg.dst_addr_width	= DMA_SLAVE_BUSWIDTH_4_BYTES;
>> +	dma_cfg.dst_maxburst	= LEDC_FIFO_DEPTH / 2;
>> +	ret = dmaengine_slave_config(priv->dma_chan, &dma_cfg);
>> +	if (ret)
>> +		return ret;
>> +
>> +	priv->buffer = dma_alloc_wc(dmaengine_get_dma_device(priv->dma_chan),
>> +				    LEDS_TO_BYTES(priv->num_leds),
>> +				    &priv->dma_handle, GFP_KERNEL);
>> +	if (!priv->buffer)
>> +		return -ENOMEM;
>> +
>> +	irq = platform_get_irq(pdev, 0);
>> +	if (irq < 0)
>> +		return irq;
>> +
>> +	ret = devm_request_irq(dev, irq, sun50i_r329_ledc_irq,
>> +			       0, dev_name(dev), priv);
>> +	if (ret)
>> +		return ret;
>> +
>> +	ret = sun50i_r329_ledc_resume(dev);
>> +	if (ret)
>> +		return ret;
> 
> You seem to fill the runtime_pm hooks, but only call them directly and
> never enable runtime_pm on that device, is that intentional?

Yes. I did not want to delay the initial version by adding runtime PM
(and debugging the refcounts) when the driver already works now.
However, I had runtime/system PM in mind while writing the driver.

If you think it is too confusing, I could rename the functions to
something like sun50i_r329_ledc_hw_init / sun50i_r329_ledc_hw_exit.

Regards,
Samuel