On 12.06.2018 02:03, Dmitry Osipenko wrote:
> On Monday, 11 June 2018 23:52:22 MSK Stefan Agner wrote:
>> Add support for the NAND flash controller found on NVIDIA
>> Tegra 2 SoCs. This implementation does not make use of the
>> command queue feature. Regular operations/data transfers are
>> done in PIO mode. Page read/writes with hardware ECC make
>> use of the DMA for data transfer.
>>
>> Signed-off-by: Lucas Stach <dev@xxxxxxxxxx>
>> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
>> ---
>> MAINTAINERS | 7 +
>> drivers/mtd/nand/raw/Kconfig | 6 +
>> drivers/mtd/nand/raw/Makefile | 1 +
>> drivers/mtd/nand/raw/tegra_nand.c | 1248 +++++++++++++++++++++++++++++
>> 4 files changed, 1262 insertions(+)
>> create mode 100644 drivers/mtd/nand/raw/tegra_nand.c
>>
[snip]
>> +static int tegra_nand_cmd(struct nand_chip *chip,
>> + const struct nand_subop *subop)
>> +{
>> + const struct nand_op_instr *instr;
>> + const struct nand_op_instr *instr_data_in = NULL;
>> + struct tegra_nand_controller *ctrl = to_tegra_ctrl(chip->controller);
>> + unsigned int op_id, size = 0, offset = 0;
>> + bool first_cmd = true;
>> + u32 reg, cmd = 0;
>> + int ret;
>> +
>> + for (op_id = 0; op_id < subop->ninstrs; op_id++) {
>> + unsigned int naddrs, i;
>> + const u8 *addrs;
>> + u32 addr1 = 0, addr2 = 0;
>> +
>> + instr = &subop->instrs[op_id];
>> +
>> + switch (instr->type) {
>> + case NAND_OP_CMD_INSTR:
>> + if (first_cmd) {
>> + cmd |= COMMAND_CLE;
>> + writel_relaxed(instr->ctx.cmd.opcode,
>> + ctrl->regs + CMD_REG1);
>> + } else {
>> + cmd |= COMMAND_SEC_CMD;
>> + writel_relaxed(instr->ctx.cmd.opcode,
>> + ctrl->regs + CMD_REG2);
>> + }
>> + first_cmd = false;
>> + break;
>> + case NAND_OP_ADDR_INSTR:
>> + offset = nand_subop_get_addr_start_off(subop, op_id);
>> + naddrs = nand_subop_get_num_addr_cyc(subop, op_id);
>> + addrs = &instr->ctx.addr.addrs[offset];
>> +
>> + cmd |= COMMAND_ALE | COMMAND_ALE_SIZE(naddrs);
>> + for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
>> + addr1 |= *addrs++ << (BITS_PER_BYTE * i);
>> + naddrs -= i;
>> + for (i = 0; i < min_t(unsigned int, 4, naddrs); i++)
>> + addr2 |= *addrs++ << (BITS_PER_BYTE * i);
>> + writel_relaxed(addr1, ctrl->regs + ADDR_REG1);
>> + writel_relaxed(addr2, ctrl->regs + ADDR_REG2);
>> + break;
>> +
>> + case NAND_OP_DATA_IN_INSTR:
>> + size = nand_subop_get_data_len(subop, op_id);
>> + offset = nand_subop_get_data_start_off(subop, op_id);
>> +
>> + cmd |= COMMAND_TRANS_SIZE(size) | COMMAND_PIO |
>> + COMMAND_RX | COMMAND_A_VALID;
>> +
>> + instr_data_in = instr;
>> + break;
>> +
>> + case NAND_OP_DATA_OUT_INSTR:
>> + size = nand_subop_get_data_len(subop, op_id);
>> + offset = nand_subop_get_data_start_off(subop, op_id);
>> +
>> + cmd |= COMMAND_TRANS_SIZE(size) | COMMAND_PIO |
>> + COMMAND_TX | COMMAND_A_VALID;
>> +
>> + memcpy(®, instr->ctx.data.buf.out + offset, size);
>> + writel_relaxed(reg, ctrl->regs + RESP);
>> +
>> + break;
>> + case NAND_OP_WAITRDY_INSTR:
>> + cmd |= COMMAND_RBSY_CHK;
>> + break;
>> +
>> + }
>> + }
>> +
>> + cmd |= COMMAND_GO | COMMAND_CE(ctrl->cur_cs);
>> + writel_relaxed(cmd, ctrl->regs + COMMAND);
>> + ret = wait_for_completion_io_timeout(&ctrl->command_complete,
>> + msecs_to_jiffies(500));
>
> It's not obvious to me whether _io_ variant is appropriate to use here, would
> be nice if somebody could clarify that. Maybe block/ already does the IO
> accounting itself and hence the IO time would be counted twice in that case.
Good that you bring this up.
I don't think that there is any higher layer which could take care of
accounting. Usually, with raw nand there is no block layer involved
anyway.
In a quick test it seems that only when using wait_for_completion_io I/O
is properly accounted in the "wait" section of top.
So far only a single driver (omap2) used the _io variant, but I think it
is the right thing to do! After all, it is I/O...
Boris or any other MTD maintainer, any comment on this?
--
Stefan
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