arch/powerpc/platforms/powermac/low_i2c.c

Source file repositories/reference/linux-study-clean/arch/powerpc/platforms/powermac/low_i2c.c

File Facts

System
Linux kernel
Corpus path
arch/powerpc/platforms/powermac/low_i2c.c
Extension
.c
Size
36461 bytes
Lines
1484
Domain
Architecture Layer
Bucket
arch/powerpc
Inferred role
Architecture Layer: exported/initcall integration point
Status
integration implementation candidate

Why This File Exists

CPU and platform-specific kernel glue: boot entry, traps, syscall entry, interrupts, page tables, context switch, and low-level barriers.

Dependency Surface

Detected Declarations

Annotated Snippet

struct pmu_i2c_hdr {
	u8	bus;
	u8	mode;
	u8	bus2;
	u8	address;
	u8	sub_addr;
	u8	comb_addr;
	u8	count;
	u8	data[];
};

static void pmu_i2c_complete(struct adb_request *req)
{
	complete(req->arg);
}

static int pmu_i2c_xfer(struct pmac_i2c_bus *bus, u8 addrdir, int subsize,
			u32 subaddr, u8 *data, int len)
{
	struct adb_request *req = bus->hostdata;
	struct pmu_i2c_hdr *hdr = (struct pmu_i2c_hdr *)&req->data[1];
	struct completion comp;
	int read = addrdir & 1;
	int retry;
	int rc = 0;

	/* For now, limit ourselves to 16 bytes transfers */
	if (len > 16)
		return -EINVAL;

	init_completion(&comp);

	for (retry = 0; retry < 16; retry++) {
		memset(req, 0, sizeof(struct adb_request));
		hdr->bus = bus->channel;
		hdr->count = len;

		switch(bus->mode) {
		case pmac_i2c_mode_std:
			if (subsize != 0)
				return -EINVAL;
			hdr->address = addrdir;
			hdr->mode = PMU_I2C_MODE_SIMPLE;
			break;
		case pmac_i2c_mode_stdsub:
		case pmac_i2c_mode_combined:
			if (subsize != 1)
				return -EINVAL;
			hdr->address = addrdir & 0xfe;
			hdr->comb_addr = addrdir;
			hdr->sub_addr = subaddr;
			if (bus->mode == pmac_i2c_mode_stdsub)
				hdr->mode = PMU_I2C_MODE_STDSUB;
			else
				hdr->mode = PMU_I2C_MODE_COMBINED;
			break;
		default:
			return -EINVAL;
		}

		reinit_completion(&comp);
		req->data[0] = PMU_I2C_CMD;
		req->reply[0] = 0xff;
		req->nbytes = sizeof(struct pmu_i2c_hdr) + 1;
		req->done = pmu_i2c_complete;
		req->arg = &comp;
		if (!read && len) {
			memcpy(hdr->data, data, len);
			req->nbytes += len;
		}
		rc = pmu_queue_request(req);
		if (rc)
			return rc;
		wait_for_completion(&comp);
		if (req->reply[0] == PMU_I2C_STATUS_OK)
			break;
		msleep(15);
	}
	if (req->reply[0] != PMU_I2C_STATUS_OK)
		return -EIO;

	for (retry = 0; retry < 16; retry++) {
		memset(req, 0, sizeof(struct adb_request));

		/* I know that looks like a lot, slow as hell, but darwin
		 * does it so let's be on the safe side for now
		 */
		msleep(15);

		hdr->bus = PMU_I2C_BUS_STATUS;

Annotation

Implementation Notes