From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bin Meng Date: Fri, 18 Oct 2019 10:32:05 +0800 Subject: [U-Boot] [PATCH v2 14/38] spi: Add support for memory-mapped flash In-Reply-To: References: <20190925141147.191166-1-sjg@chromium.org> <20190925141147.191166-15-sjg@chromium.org> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Simon, On Fri, Oct 18, 2019 at 10:22 AM Simon Glass wrote: > > Hi, > > On Thu, 17 Oct 2019 at 08:28, Simon Glass wrote: > > > > Hi Vignesh, > > > > On Wed, 16 Oct 2019 at 04:28, Vignesh Raghavendra wrote: > > > > > > Hi Simon, > > > > > > On 12/10/19 10:03 AM, Bin Meng wrote: > > > > Hi Simon, > > > > > > > > On Sat, Oct 12, 2019 at 11:08 AM Simon Glass wrote: > > > >> > > > >> Hi Bin, > > > >> > > > >> On Wed, 9 Oct 2019 at 07:55, Bin Meng wrote: > > > >>> > > > >>> Hi Simon, > > > >>> > > > >>> On Wed, Sep 25, 2019 at 10:12 PM Simon Glass wrote: > > > >>>> > > > >>>> On x86 platforms the SPI flash can be mapped into memory so that the > > > >>>> contents can be read with normal memory accesses. > > > >>>> > > > >>>> Add a new SPI flash method to find the location of the SPI flash in > > > >>>> memory. This differs from the existing device-tree "memory-map" mechanism > > > >>>> in that the location can be discovered at run-time. > > > >>>> > > > > > > Whats is the usecase? Why can't spi_flash_read() be used instead? > > > Flash + Controller driver can underneath take care of using memory > > > mapped mode to read data from flash right while making sure that access > > > is within valid window? > > > > I can see spi_flash_read_dm() but it does not support returning a > > pointer to the data, only reading it. > > > > Also I cannot find any documentation about any of this. I've been > > looking in the doc/ directory. > > > > I found the spi_mem.h file but it doesn't mention the meaning of the > > in and out buffer pointers so I don't know how to use them. > > > > Is there an API missing or just comments/documentation? > > Apart from this I have found that the ich_spi driver does not work for > APL since it apparently only supports 'hardware sequencing'. I did try > getting software sequencing to work, but no dice. > > In addition, I found that enabling SPI flash, etc. added about 6KB of code! > > So I think it might be best to have two SPI drivers for x86 - one for > software sequencing and one for hardware? So if this is true, I think we can create Kconfig options (HW_SEQ and SW_SEQ) for ICH SPI driver, and select either one in the SoC Kconfig file. But I see from the Linux kernel driver, it has: 300static int intel_spi_init(struct intel_spi *ispi) 301{ 302 u32 opmenu0, opmenu1, lvscc, uvscc, val; 303 int i; 304 305 switch (ispi->info->type) { 306 case INTEL_SPI_BYT: 307 ispi->sregs = ispi->base + BYT_SSFSTS_CTL; 308 ispi->pregs = ispi->base + BYT_PR; 309 ispi->nregions = BYT_FREG_NUM; 310 ispi->pr_num = BYT_PR_NUM; 311 ispi->swseq_reg = true; 312 313 if (writeable) { 314 /* Disable write protection */ 315 val = readl(ispi->base + BYT_BCR); 316 if (!(val & BYT_BCR_WPD)) { 317 val |= BYT_BCR_WPD; 318 writel(val, ispi->base + BYT_BCR); 319 val = readl(ispi->base + BYT_BCR); 320 } 321 322 ispi->writeable = !!(val & BYT_BCR_WPD); 323 } 324 325 break; 326 327 case INTEL_SPI_LPT: 328 ispi->sregs = ispi->base + LPT_SSFSTS_CTL; 329 ispi->pregs = ispi->base + LPT_PR; 330 ispi->nregions = LPT_FREG_NUM; 331 ispi->pr_num = LPT_PR_NUM; 332 ispi->swseq_reg = true; 333 break; 334 335 case INTEL_SPI_BXT: 336 ispi->sregs = ispi->base + BXT_SSFSTS_CTL; 337 ispi->pregs = ispi->base + BXT_PR; 338 ispi->nregions = BXT_FREG_NUM; 339 ispi->pr_num = BXT_PR_NUM; 340 ispi->erase_64k = true; 341 break; So for INTEL_SPI_BXT (which is for ApolloLake I believe) ispi->swseq_reg is not set to true which means it uses hardware sequencer, which seems to contradict with what you found. Regards, Bin