Hi, On 5/11/26 2:07 PM, Sascha Hauer wrote: > Add reusable ADMA2 (32-bit and 64-bit) support to the SDHCI core so > drivers can opt in to ADMA without each having to reimplement descriptor > table management. > > A driver enables ADMA by calling sdhci_setup_adma() after > sdhci_setup_host(). The helper allocates a DMA-coherent descriptor > table sized for SDHCI_DEFAULT_ADMA_DESCS entries (drivers can override > adma_table_cnt before calling), picks the descriptor format based on > SDHCI_USE_64_BIT_DMA, sets SDHCI_USE_ADMA in host->flags and caps > mci->max_req_size so the MCI core splits requests to fit. From there, > sdhci_setup_data_dma() builds an ADMA2 descriptor chain for the > contiguous transfer buffer (one descriptor per up-to-64 KiB chunk plus > a terminating nop/end entry) and programs SDHCI_ADMA_ADDRESS instead > of the SDMA address. sdhci_config_dma() now selects ADMA32/ADMA64 in > HOST_CONTROL accordingly. > > If sdhci_setup_adma() fails (no SDHCI_CAN_DO_ADMA2, no memory, or > unaligned table), the host transparently falls back to the existing > SDMA path.
See below for feedback. > > Assisted-by: Claude Opus 4.7 <[email protected]> > Signed-off-by: Sascha Hauer <[email protected]> > --- > drivers/mci/sdhci.c | 154 > +++++++++++++++++++++++++++++++++++++++++++++++++++- > drivers/mci/sdhci.h | 59 ++++++++++++++++++++ > 2 files changed, 212 insertions(+), 1 deletion(-) > > diff --git a/drivers/mci/sdhci.c b/drivers/mci/sdhci.c > index f7172347e1..0c3ca69e9a 100644 > --- a/drivers/mci/sdhci.c > +++ b/drivers/mci/sdhci.c > @@ -585,6 +585,13 @@ static void sdhci_config_dma(struct sdhci *host) > ctrl = sdhci_read8(host, SDHCI_HOST_CONTROL); > /* Note if DMA Select is zero then SDMA is selected */ > ctrl &= ~SDHCI_CTRL_DMA_MASK; > + > + if (host->flags & SDHCI_USE_ADMA) { > + ctrl |= SDHCI_CTRL_ADMA32; > + if (host->flags & SDHCI_USE_64_BIT_DMA && !host->v4_mode) > + ctrl |= SDHCI_CTRL_ADMA64; > + } > + > sdhci_write8(host, SDHCI_HOST_CONTROL, ctrl); > > if (host->flags & SDHCI_USE_64_BIT_DMA) { > @@ -601,11 +608,67 @@ static void sdhci_config_dma(struct sdhci *host) > } > } > > +static void sdhci_adma_write_desc(struct sdhci *host, void **desc, > + dma_addr_t addr, int len, unsigned int cmd) > +{ > + struct sdhci_adma2_64_desc *dma_desc = *desc; This should be a union between sdhci_adma2_32_desc and sdhci_adma2_64_desc. > + > + /* 32-bit and 64-bit descriptors share these fields. */ > + dma_desc->cmd = cpu_to_le16(cmd); > + dma_desc->len = cpu_to_le16(len); > + dma_desc->addr_lo = cpu_to_le32(lower_32_bits(addr)); > + > + if (host->flags & SDHCI_USE_64_BIT_DMA) > + dma_desc->addr_hi = cpu_to_le32(upper_32_bits(addr)); On a 64-bit system without SDHCI_USE_64_BIT_DMA, but with a 64-bit addr, we will end up with memory corruption here. Please add at least a BUG, so it fails reliably or propagate an error. > + > + *desc += host->desc_sz; > +} > +EXPORT_SYMBOL_GPL(sdhci_adma_write_desc); Why export a static symbol? > + > +/* > + * Build the ADMA2 descriptor table for a single contiguous DMA buffer. > + * Each entry of the table covers up to SDHCI_ADMA2_MAX_LEN bytes; longer > + * transfers are split across multiple descriptors. > + */ > +static int sdhci_adma_build_table(struct sdhci *host, dma_addr_t addr, > + unsigned int len) > +{ > + void *desc = host->adma_table; > + void *desc_end = host->adma_table + host->adma_table_sz; > + > + while (len) { > + unsigned int chunk = min_t(unsigned int, len, > + SDHCI_ADMA2_MAX_LEN); I think the min_t is unneeded and if it is, just give len the same type as SDHCI_ADMA2_MAX_LEN? > + > + if (desc + host->desc_sz > desc_end) > + return -ENOSPC; > + > + /* > + * The length field is 16-bit; a length of 0 encodes > + * SDHCI_ADMA2_MAX_LEN bytes per the SD Host Controller > + * specification. > + */ > + sdhci_adma_write_desc(host, &desc, addr, chunk & 0xffff, > + ADMA2_TRAN_VALID); > + addr += chunk; > + len -= chunk; > + } > + > + if (desc + host->desc_sz > desc_end) > + return -ENOSPC; Nitpick: I think it would be cleaner to move this check into sdhci_adma_write_desc(), so it returns an error on out-of-bound write and just propagate the error instead of redoing the same if clause here and in the loop. > + > + /* Append a terminating descriptor (nop, end, valid). */ > + sdhci_adma_write_desc(host, &desc, 0, 0, ADMA2_NOP_END_VALID); > + > + return 0; > +} > + > void sdhci_setup_data_dma(struct sdhci *sdhci, struct mci_data *data, > dma_addr_t *dma) > { > struct device *dev = sdhci_dev(sdhci); > int nbytes; > + int ret; > > if (!data) { > if (dma) > @@ -633,7 +696,22 @@ void sdhci_setup_data_dma(struct sdhci *sdhci, struct > mci_data *data, > } > > sdhci_config_dma(sdhci); > - sdhci_set_sdma_addr(sdhci, *dma); > + > + if (sdhci->flags & SDHCI_USE_ADMA) { > + ret = sdhci_adma_build_table(sdhci, *dma, nbytes); > + if (ret) { > + dev_err(dev, "ADMA table build failed: %pe\n", > + ERR_PTR(ret)); > + dma_unmap_single(dev, *dma, nbytes, > + (data->flags & MMC_DATA_READ) ? > + DMA_FROM_DEVICE : DMA_TO_DEVICE); Why is the data umapped here?! > + *dma = SDHCI_NO_DMA; > + return; > + } > + sdhci_set_adma_addr(sdhci, sdhci->adma_addr); > + } else { > + sdhci_set_sdma_addr(sdhci, *dma); > + } > } > > void sdhci_teardown_data(struct sdhci *sdhci, > @@ -1213,3 +1291,77 @@ int sdhci_setup_host(struct sdhci *host) > > return 0; > } > + > +/** > + * sdhci_setup_adma() - allocate ADMA descriptor table and enable ADMA > + * @host: sdhci host > + * > + * Allocate a DMA-coherent ADMA2 descriptor table and mark the host as > + * ADMA-capable so subsequent calls to sdhci_setup_data_dma() use ADMA > + * instead of SDMA. Drivers must call this after sdhci_setup_host() since > + * it relies on the SDHCI_USE_64_BIT_DMA flag established there. > + * > + * The descriptor count defaults to SDHCI_DEFAULT_ADMA_DESCS, which caps > + * the largest single transfer at SDHCI_DEFAULT_ADMA_DESCS * > + * SDHCI_ADMA2_MAX_LEN bytes. Drivers can override host->adma_table_cnt > + * before calling to allocate a different size. > + * > + * Returns 0 on success or a negative error code on failure. On failure > + * the host falls back to SDMA. > + */ > +int sdhci_setup_adma(struct sdhci *host) > +{ > + struct device *dev = sdhci_dev(host); > + struct mci_host *mci = host->mci; > + dma_addr_t dma; > + void *buf; > + > + BUG_ON(!mci); > + > + /* > + * Without a controller capability bit ADMA2 cannot be used. Don't > + * fail loudly: the driver may have called us speculatively, just > + * leave SDMA as the fallback. > + */ > + if (!(host->caps & SDHCI_CAN_DO_ADMA2)) > + return -ENOTSUPP; > + > + if (host->flags & SDHCI_USE_64_BIT_DMA) > + host->desc_sz = SDHCI_ADMA2_64_DESC_SZ(host); > + else > + host->desc_sz = SDHCI_ADMA2_32_DESC_SZ; > + > + if (!host->adma_table_cnt) > + host->adma_table_cnt = SDHCI_DEFAULT_ADMA_DESCS; > + > + host->adma_table_sz = host->adma_table_cnt * host->desc_sz; > + > + buf = dma_alloc_coherent(dev, host->adma_table_sz, &dma); > + if (!buf) > + return -ENOMEM; > + > + host->adma_table = buf; > + host->adma_addr = dma; > + host->flags |= SDHCI_USE_ADMA; > + > + /* > + * One descriptor handles up to SDHCI_ADMA2_MAX_LEN bytes; the last > + * one is reserved for the terminating entry. > + */ > + mci->max_req_size = (host->adma_table_cnt - 1) * SDHCI_ADMA2_MAX_LEN; > + > + return 0; > +} > +EXPORT_SYMBOL_GPL(sdhci_setup_adma); > + > +void sdhci_release_adma(struct sdhci *host) > +{ > + if (!(host->flags & SDHCI_USE_ADMA)) > + return; > + > + dma_free_coherent(sdhci_dev(host), host->adma_table, host->adma_addr, > + host->adma_table_sz); > + host->adma_table = NULL; Why zero host->adma_table, but not host->adma_addr? > + host->flags &= ~SDHCI_USE_ADMA; > +} > +EXPORT_SYMBOL_GPL(sdhci_release_adma); Cheers, Ahmad -- Pengutronix e.K. | | Steuerwalder Str. 21 | http://www.pengutronix.de/ | 31137 Hildesheim, Germany | Phone: +49-5121-206917-0 | Amtsgericht Hildesheim, HRA 2686 | Fax: +49-5121-206917-5555 |
