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SubjectRe: [PATCH 6/9] mmc: mmci: sdmmc: add execute tuning with delay block
On Fri, 10 Jan 2020 at 14:49, Ludovic Barre <ludovic.barre@st.com> wrote:
>
> The hardware delay block is used to align the sampling clock on
> the data received by SDMMC. It is mandatory for SDMMC to
> support the SDR104 mode. The delay block is used to generate
> an output clock which is dephased from the input clock.
> The phase of the output clock must be programmed by the execute
> tuning interface.
>
> Signed-off-by: Ludovic Barre <ludovic.barre@st.com>
> ---
> drivers/mmc/host/mmci_stm32_sdmmc.c | 147 ++++++++++++++++++++++++++++
> 1 file changed, 147 insertions(+)
>
> diff --git a/drivers/mmc/host/mmci_stm32_sdmmc.c b/drivers/mmc/host/mmci_stm32_sdmmc.c
> index df08f6662431..10059fa19f4a 100644
> --- a/drivers/mmc/host/mmci_stm32_sdmmc.c
> +++ b/drivers/mmc/host/mmci_stm32_sdmmc.c
> @@ -3,10 +3,13 @@
> * Copyright (C) STMicroelectronics 2018 - All Rights Reserved
> * Author: Ludovic.barre@st.com for STMicroelectronics.
> */
> +#include <linux/bitfield.h>
> #include <linux/delay.h>
> #include <linux/dma-mapping.h>
> +#include <linux/iopoll.h>
> #include <linux/mmc/host.h>
> #include <linux/mmc/card.h>
> +#include <linux/of_address.h>
> #include <linux/reset.h>
> #include <linux/scatterlist.h>
> #include "mmci.h"
> @@ -14,6 +17,20 @@
> #define SDMMC_LLI_BUF_LEN PAGE_SIZE
> #define SDMMC_IDMA_BURST BIT(MMCI_STM32_IDMABNDT_SHIFT)
>
> +#define DLYB_CR 0x0
> +#define DLYB_CR_DEN BIT(0)
> +#define DLYB_CR_SEN BIT(1)
> +
> +#define DLYB_CFGR 0x4
> +#define DLYB_CFGR_SEL_MASK GENMASK(3, 0)
> +#define DLYB_CFGR_UNIT_MASK GENMASK(14, 8)
> +#define DLYB_CFGR_LNG_MASK GENMASK(27, 16)
> +#define DLYB_CFGR_LNGF BIT(31)
> +
> +#define DLYB_NB_DELAY 11
> +#define DLYB_CFGR_SEL_MAX (DLYB_NB_DELAY + 1)
> +#define DLYB_CFGR_UNIT_MAX 127

[...]

> +static int sdmmc_dlyb_lng_tuning(struct mmci_host *host)
> +{
> + struct sdmmc_dlyb *dlyb = host->variant_priv;
> + u32 cfgr;
> + int i, lng, ret;
> +
> + for (i = 0; i <= DLYB_CFGR_UNIT_MAX; i++) {
> + sdmmc_dlyb_set_cfgr(dlyb, i, DLYB_CFGR_SEL_MAX, true);
> +
> + ret = readl_relaxed_poll_timeout(dlyb->base + DLYB_CFGR, cfgr,
> + (cfgr & DLYB_CFGR_LNGF),
> + 1, 1000);

I suggest you introduce a define for this timeout, in the top of the file.

> + if (ret) {
> + dev_warn(mmc_dev(host->mmc),
> + "delay line cfg timeout unit:%d cfgr:%d\n",
> + i, cfgr);
> + continue;
> + }
> +
> + lng = FIELD_GET(DLYB_CFGR_LNG_MASK, cfgr);
> + if (lng < BIT(DLYB_NB_DELAY) && lng > 0)
> + break;
> + }
> +
> + if (i > DLYB_CFGR_UNIT_MAX)
> + return -EINVAL;
> +
> + dlyb->unit = i;
> + dlyb->max = __fls(lng);
> +
> + return 0;
> +}
> +
> +static int sdmmc_dlyb_phase_tuning(struct mmci_host *host, u32 opcode)
> +{
> + struct sdmmc_dlyb *dlyb = host->variant_priv;
> + int cur_len = 0, max_len = 0, end_of_len = 0;
> + int phase;
> +
> + for (phase = 0; phase <= dlyb->max; phase++) {
> + sdmmc_dlyb_set_cfgr(dlyb, dlyb->unit, phase, false);
> +
> + if (mmc_send_tuning(host->mmc, opcode, NULL)) {
> + cur_len = 0;
> + } else {
> + cur_len++;
> + if (cur_len > max_len) {
> + max_len = cur_len;
> + end_of_len = phase;
> + }
> + }
> + }
> +
> + if (!max_len) {
> + dev_err(mmc_dev(host->mmc), "no tuning point found\n");
> + return -EINVAL;
> + }
> +
> + phase = end_of_len - max_len / 2;
> + sdmmc_dlyb_set_cfgr(dlyb, dlyb->unit, phase, false);
> +
> + dev_dbg(mmc_dev(host->mmc), "unit:%d max_dly:%d phase:%d\n",
> + dlyb->unit, dlyb->max, phase);
> +
> + return 0;
> +}
> +
> +static int sdmmc_execute_tuning(struct mmc_host *mmc, u32 opcode)
> +{
> + struct mmci_host *host = mmc_priv(mmc);
> + struct sdmmc_dlyb *dlyb = host->variant_priv;
> +
> + if (!dlyb || !dlyb->base)
> + return -EINVAL;
> +
> + if (sdmmc_dlyb_lng_tuning(host))
> + return -EINVAL;
> +
> + return sdmmc_dlyb_phase_tuning(host, opcode);

What happens to the tuning registers when the controller device
becomes runtime suspended? Would it possible that the values gets lost
and then they need to be restored in runtime resume?

> +}
> +
> static struct mmci_host_ops sdmmc_variant_ops = {
> .validate_data = sdmmc_idma_validate_data,
> .prep_data = sdmmc_idma_prep_data,
> @@ -338,5 +469,21 @@ static struct mmci_host_ops sdmmc_variant_ops = {
>
> void sdmmc_variant_init(struct mmci_host *host)
> {
> + struct device_node *np = host->mmc->parent->of_node;
> + void __iomem *base_dlyb;
> + struct sdmmc_dlyb *dlyb;
> +
> host->ops = &sdmmc_variant_ops;
> +
> + base_dlyb = devm_of_iomap(mmc_dev(host->mmc), np, 1, NULL);
> + if (IS_ERR(base_dlyb))
> + return;
> +
> + dlyb = devm_kzalloc(mmc_dev(host->mmc), sizeof(*dlyb), GFP_KERNEL);
> + if (!dlyb)
> + return;
> +
> + dlyb->base = base_dlyb;
> + host->variant_priv = dlyb;
> + host->mmc_ops->execute_tuning = sdmmc_execute_tuning;
> }
> --
> 2.17.1
>

Kind regards
Uffe

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