drivers/memory/brcmstb_memc.c

Source file repositories/reference/linux-study-clean/drivers/memory/brcmstb_memc.c

File Facts

System
Linux kernel
Corpus path
drivers/memory/brcmstb_memc.c
Extension
.c
Size
5851 bytes
Lines
248
Domain
Driver Families
Bucket
drivers/memory
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

struct brcmstb_memc_data {
	u32 srpd_offset;
};

struct brcmstb_memc {
	struct device *dev;
	void __iomem *ddr_ctrl;
	unsigned int timeout_cycles;
	u32 frequency;
	u32 srpd_offset;
};

static int brcmstb_memc_uses_lpddr45(struct brcmstb_memc *memc)
{
	void __iomem *config = memc->ddr_ctrl + REG_MEMC_CNTRLR_CONFIG;
	u32 reg;

	reg = readl_relaxed(config) & CNTRLR_CONFIG_MASK;

	return reg == CNTRLR_CONFIG_LPDDR4_SHIFT ||
	       reg == CNTRLR_CONFIG_LPDDR5_SHIFT;
}

static int brcmstb_memc_srpd_config(struct brcmstb_memc *memc,
				    unsigned int cycles)
{
	void __iomem *cfg = memc->ddr_ctrl + memc->srpd_offset;
	u32 val;

	/* Max timeout supported in HW */
	if (cycles > INACT_COUNT_MASK)
		return -EINVAL;

	memc->timeout_cycles = cycles;

	val = (cycles << INACT_COUNT_SHIFT) & INACT_COUNT_MASK;
	if (cycles)
		val |= BIT(SRPD_EN_SHIFT);

	writel_relaxed(val, cfg);
	/* Ensure the write is committed to the controller */
	(void)readl_relaxed(cfg);

	return 0;
}

static ssize_t frequency_show(struct device *dev,
			      struct device_attribute *attr, char *buf)
{
	struct brcmstb_memc *memc = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", memc->frequency);
}

static ssize_t srpd_show(struct device *dev,
			 struct device_attribute *attr, char *buf)
{
	struct brcmstb_memc *memc = dev_get_drvdata(dev);

	return sprintf(buf, "%d\n", memc->timeout_cycles);
}

static ssize_t srpd_store(struct device *dev, struct device_attribute *attr,
			  const char *buf, size_t count)
{
	struct brcmstb_memc *memc = dev_get_drvdata(dev);
	unsigned int val;
	int ret;

	/*
	 * Cannot change the inactivity timeout on LPDDR4 chips because the
	 * dynamic tuning process will also get affected by the inactivity
	 * timeout, thus making it non functional.
	 */
	if (brcmstb_memc_uses_lpddr45(memc))
		return -EOPNOTSUPP;

	ret = kstrtouint(buf, 10, &val);
	if (ret < 0)
		return ret;

	ret = brcmstb_memc_srpd_config(memc, val);
	if (ret)
		return ret;

	return count;
}

static DEVICE_ATTR_RO(frequency);
static DEVICE_ATTR_RW(srpd);

Annotation

Implementation Notes