static int jz4780_efuse_probe()

in jz4780-efuse.c [139:216]

• 52 lines of code
• 9 McCabe index (conditional complexity)

static int jz4780_efuse_probe(struct platform_device *pdev)
{
	struct nvmem_device *nvmem;
	struct jz4780_efuse *efuse;
	struct nvmem_config cfg;
	unsigned long clk_rate;
	unsigned long rd_adj;
	unsigned long rd_strobe;
	struct device *dev = &pdev->dev;
	void __iomem *regs;
	int ret;

	efuse = devm_kzalloc(dev, sizeof(*efuse), GFP_KERNEL);
	if (!efuse)
		return -ENOMEM;

	regs = devm_platform_ioremap_resource(pdev, 0);
	if (IS_ERR(regs))
		return PTR_ERR(regs);

	efuse->map = devm_regmap_init_mmio(dev, regs,
					   &jz4780_efuse_regmap_config);
	if (IS_ERR(efuse->map))
		return PTR_ERR(efuse->map);

	efuse->clk = devm_clk_get(&pdev->dev, NULL);
	if (IS_ERR(efuse->clk))
		return PTR_ERR(efuse->clk);

	ret = clk_prepare_enable(efuse->clk);
	if (ret < 0)
		return ret;

	ret = devm_add_action_or_reset(&pdev->dev,
				       clk_disable_unprepare_helper,
				       efuse->clk);
	if (ret < 0)
		return ret;

	clk_rate = clk_get_rate(efuse->clk);

	efuse->dev = dev;

	/*
	 * rd_adj and rd_strobe are 4 bit values
	 * conditions:
	 *   bus clk_period * (rd_adj + 1) > 6.5ns
	 *   bus clk_period * (rd_adj + 5 + rd_strobe) > 35ns
	 *   i.e. rd_adj >= 6.5ns / clk_period
	 *   i.e. rd_strobe >= 35 ns / clk_period - 5 - rd_adj + 1
	 * constants:
	 *   1 / 6.5ns == 153846154 Hz
	 *   1 / 35ns == 28571429 Hz
	 */

	rd_adj = clk_rate / 153846154;
	rd_strobe = clk_rate / 28571429 - 5 - rd_adj + 1;

	if (rd_adj > EFUCFG_RD_ADJ_MASK ||
	    rd_strobe > EFUCFG_RD_STR_MASK) {
		dev_err(&pdev->dev, "Cannot set clock configuration\n");
		return -EINVAL;
	}

	regmap_update_bits(efuse->map, JZ_EFUCFG,
			   (EFUCFG_RD_ADJ_MASK << EFUCFG_RD_ADJ_SHIFT) |
			   (EFUCFG_RD_STR_MASK << EFUCFG_RD_STR_SHIFT),
			   (rd_adj << EFUCFG_RD_ADJ_SHIFT) |
			   (rd_strobe << EFUCFG_RD_STR_SHIFT));

	cfg = jz4780_efuse_nvmem_config;
	cfg.dev = &pdev->dev;
	cfg.priv = efuse;

	nvmem = devm_nvmem_register(dev, &cfg);

	return PTR_ERR_OR_ZERO(nvmem);
}