Messages in this thread Patch in this message | | | Date | Tue, 29 Oct 2013 13:31:15 -0500 | From | Felipe Balbi <> | Subject | Re: [PATCH 1/2] spi: add Intel Mid SSP driver |
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Hi,
On Tue, Oct 29, 2013 at 11:05:49AM -0700, David Cohen wrote: > diff --git a/drivers/spi/spi-intel-mid-ssp.c b/drivers/spi/spi-intel-mid-ssp.c > new file mode 100644 > index 0000000..b3b9fe8 > --- /dev/null > +++ b/drivers/spi/spi-intel-mid-ssp.c > @@ -0,0 +1,1506 @@ > +/* > + * spi-intel-mid-ssp.c > + * This driver supports Bulverde SSP core used on Intel MID platforms > + * It supports SSP of Moorestown & Medfield platforms and handles clock > + * slave & master modes. > + * > + * Copyright (c) 2013, Intel Corporation. > + * Contacts: Ning Li <ning.li@intel.com> > + * David Cohen <david.a.cohen@linux.intel.com> > + * > + * This program is free software; you can redistribute it and/or modify it > + * under the terms and conditions of the GNU General Public License, > + * version 2, as published by the Free Software Foundation. > + * > + * This program is distributed in the hope it will be useful, but WITHOUT > + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or > + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for > + * more details. > + * > + * You should have received a copy of the GNU General Public License along with > + * this program; if not, write to the Free Software Foundation, Inc., > + * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA. > + * > + */ > + > +/* > + * Note: > + * > + * Supports DMA and non-interrupt polled transfers. > + * > + */ > +#include <linux/kernel.h> > +#include <linux/module.h> > +#include <linux/delay.h> > +#include <linux/interrupt.h> > +#include <linux/highmem.h> > +#include <linux/pci.h> > +#include <linux/init.h> > +#include <linux/interrupt.h> > +#include <linux/dma-mapping.h> > +#include <linux/intel_mid_dma.h> > +#include <linux/pm_qos.h> > +#include <linux/pm_runtime.h> > +#include <linux/completion.h> > +#include <asm/intel-mid.h> > + > +#include <linux/spi/spi.h> > +#include <linux/spi/intel_mid_ssp_spi.h> > + > +#define DRIVER_NAME "intel_mid_ssp_spi_unified" > + > +static int ssp_timing_wr;
this will prevent multiple instances of the same driver.
> +#ifdef DUMP_RX > +static void dump_trailer(const struct device *dev, char *buf, int len, int sz) > +{ > + int tlen1 = (len < sz ? len : sz); > + int tlen2 = ((len - sz) > sz) ? sz : (len - sz); > + unsigned char *p; > + static char msg[MAX_SPI_TRANSFER_SIZE]; > + > + memset(msg, '\0', sizeof(msg)); > + p = buf; > + while (p < buf + tlen1) > + sprintf(msg, "%s%02x", msg, (unsigned int)*p++); > + > + if (tlen2 > 0) { > + sprintf(msg, "%s .....", msg); > + p = (buf+len) - tlen2; > + while (p < buf + len) > + sprintf(msg, "%s%02x", msg, (unsigned int)*p++); > + } > + > + dev_info(dev, "DUMP: %p[0:%d ... %d:%d]:%s", buf, tlen1 - 1, > + len-tlen2, len - 1, msg); > +} > +#endif
either move this to debugfs or stub the function out ifndef DUMP_RX, then you don't need the ifdefs when calling it.
> +static inline u8 ssp_cfg_get_mode(u8 ssp_cfg) > +{ > + if (intel_mid_identify_cpu() == INTEL_MID_CPU_CHIP_TANGIER)
instead, couldn't you use driver data to pass some flags to the driver ? I can't see intel_mid_identify_cpu and having drivers depend on arch-specific code is usually a bad practice.
> + return (ssp_cfg) & 0x03; > + else
else isn't needed here
> +static inline u32 is_tx_fifo_empty(struct ssp_drv_context *sspc) > +{ > + u32 sssr;
blank line here would aid readability
> + sssr = read_SSSR(sspc->ioaddr); > + if ((sssr & SSSR_TFL_MASK) || (sssr & SSSR_TNF) == 0) > + return 0; > + else
else isn't necessary
> +static inline u32 is_rx_fifo_empty(struct ssp_drv_context *sspc) > +{ > + return ((read_SSSR(sspc->ioaddr) & SSSR_RNE) == 0);
you don't need the outter parenthesis here, GCC should've warned you, even.
> +static inline void disable_interface(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
blank line here
> + write_SSCR0(read_SSCR0(reg) & ~SSCR0_SSE, reg); > +} > + > +static inline void disable_triggers(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
and here...
> + write_SSCR1(read_SSCR1(reg) & ~sspc->cr1_sig, reg); > +} > + > + > +static void flush(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr; > + u32 i = 0; > + > + /* If the transmit fifo is not empty, reset the interface. */ > + if (!is_tx_fifo_empty(sspc)) { > + dev_err(&sspc->pdev->dev, "TX FIFO not empty. Reset of SPI IF"); > + disable_interface(sspc); > + return; > + }
not so sure, if the transmit fifo isn't empty and you reset it, you could end up corrupting data which is about to be shifted into the wire, couldn't you ?
Is this a case which would *really* happen in normal conditions ? If so, why ?
> + dev_dbg(&sspc->pdev->dev, " SSSR=%x\r\n", read_SSSR(reg)); > + while (!is_rx_fifo_empty(sspc) && (i < SPI_FIFO_SIZE + 1)) { > + read_SSDR(reg); > + i++; > + } > + WARN(i > 0, "%d words flush occured\n", i);
similarly, you could be ignoring data you *should* indeed be handling.
> + > + return;
return statement is unnecessary.
> +static int null_writer(struct ssp_drv_context *sspc)
looks like these two functions (null_\(writer\|reader\)) need some documentation. Why do they exist ?
> +static int u8_writer(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
blank line
> + if (((read_SSSR(reg) & SSSR_TFL_MASK) == SSSR_TFL_MASK) > + || (sspc->tx == sspc->tx_end)) > + return 0; > + > + write_SSDR(*(u8 *)(sspc->tx), reg); > + ++sspc->tx; > + > + return 1; > +} > + > +static int u8_reader(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
blank line
> + while ((read_SSSR(reg) & SSSR_RNE) > + && (sspc->rx < sspc->rx_end)) { > + *(u8 *)(sspc->rx) = read_SSDR(reg); > + ++sspc->rx; > + } > + > + return sspc->rx == sspc->rx_end; > +} > + > +static int u16_writer(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
blank line
> + if (((read_SSSR(reg) & SSSR_TFL_MASK) == SSSR_TFL_MASK)
the extra comparisson here is superfluous.
> + || (sspc->tx == sspc->tx_end)) > + return 0; > + > + write_SSDR(*(u16 *)(sspc->tx), reg); > + sspc->tx += 2; > + > + return 1; > +} > + > +static int u16_reader(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
blank line
> + while ((read_SSSR(reg) & SSSR_RNE) && (sspc->rx < sspc->rx_end)) { > + *(u16 *)(sspc->rx) = read_SSDR(reg); > + sspc->rx += 2; > + } > + > + return sspc->rx == sspc->rx_end; > +} > + > +static int u32_writer(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
blank line
> + if (((read_SSSR(reg) & SSSR_TFL_MASK) == SSSR_TFL_MASK)
the extra comparisson here is superfluous.
> + || (sspc->tx == sspc->tx_end)) > + return 0; > + > + write_SSDR(*(u32 *)(sspc->tx), reg); > + sspc->tx += 4; > + > + return 1; > +} > + > +static int u32_reader(struct ssp_drv_context *sspc) > +{ > + void *reg = sspc->ioaddr;
blank line
> + while ((read_SSSR(reg) & SSSR_RNE) && (sspc->rx < sspc->rx_end)) { > + *(u32 *)(sspc->rx) = read_SSDR(reg); > + sspc->rx += 4; > + } > + > + return sspc->rx == sspc->rx_end; > +} > + > +static bool chan_filter(struct dma_chan *chan, void *param) > +{ > + struct ssp_drv_context *sspc = param; > + > + if (sspc->dmac1 && chan->device->dev == &sspc->dmac1->dev) > + return true; > + > + return false; > +} > + > +/** > + * unmap_dma_buffers() - Unmap the DMA buffers used during the last transfer. > + * @sspc: Pointer to the private driver context > + */ > +static void unmap_dma_buffers(struct ssp_drv_context *sspc) > +{ > + struct device *dev = &sspc->pdev->dev; > + > + if (!sspc->dma_mapped) > + return;
blank line
> + dma_unmap_single(dev, sspc->rx_dma, sspc->len, PCI_DMA_FROMDEVICE); > + dma_unmap_single(dev, sspc->tx_dma, sspc->len, PCI_DMA_TODEVICE); > + sspc->dma_mapped = 0;
you shouldn't need this dma_mapped flag here...
> +static void ssp_spi_dma_done(void *arg) > +{ > + struct callback_param *cb_param = (struct callback_param *)arg; > + struct ssp_drv_context *sspc = cb_param->drv_context; > + struct device *dev = &sspc->pdev->dev; > + void *reg = sspc->ioaddr; > + > + if (cb_param->direction == TX_DIRECTION) > + sspc->txdma_done = 1; > + else > + sspc->rxdma_done = 1; > + > + dev_dbg(dev, "DMA callback for direction %d [RX done:%d] [TX done:%d]\n", > + cb_param->direction, sspc->rxdma_done, > + sspc->txdma_done); > + > + if (sspc->txdma_done && sspc->rxdma_done) { > + /* Clear Status Register */ > + write_SSSR(sspc->clear_sr, reg); > + dev_dbg(dev, "DMA done\n"); > + /* Disable Triggers to DMA or to CPU*/ > + disable_triggers(sspc); > + unmap_dma_buffers(sspc); > + > + queue_work(sspc->dma_wq, &sspc->complete_work);
I fail to see the need for this workstruct, why can't you call complete() directly ?
> +static irqreturn_t ssp_int(int irq, void *dev_id) > +{ > + struct ssp_drv_context *sspc = dev_id; > + void *reg = sspc->ioaddr; > + struct device *dev = &sspc->pdev->dev; > + u32 status = read_SSSR(reg); > + > + /* It should never be our interrupt since SSP will */ > + /* only trigs interrupt for under/over run. */
wrong comment style
> + if (likely(!(status & sspc->mask_sr))) > + return IRQ_NONE; > + > + if (status & SSSR_ROR || status & SSSR_TUR) { > + dev_err(dev, "--- SPI ROR or TUR occurred : SSSR=%x\n", status); > + WARN_ON(1); > + if (status & SSSR_ROR) > + dev_err(dev, "we have Overrun\n"); > + if (status & SSSR_TUR) > + dev_err(dev, "we have Underrun\n"); > + }
I would split these two caes here:
if (status & ROR) dev_WARN(dev, "Overrun\n");
if (status & TUR) dev_WARN(dev, "Underrun\n");
no need for nested ifs.
> +static void poll_transfer(unsigned long data) > +{ > + struct ssp_drv_context *sspc = (void *)data; > + > + if (sspc->tx) { > + while (sspc->tx != sspc->tx_end) { > + if (ssp_timing_wr) { > + int timeout = 100; > + /* It is used as debug UART on Tangier. Since > + baud rate = 115200, it needs at least 312us > + for one word transferring. Becuase of silicon > + issue, it MUST check SFIFOL here instead of > + TNF. It is the workaround for A0 stepping*/
wrong comment style.
> + while (--timeout && > + ((read_SFIFOL(sspc->ioaddr)) & 0xFFFF)) > + udelay(10); > + } > + sspc->write(sspc); > + sspc->read(sspc); > + } > + }
you can make this look sligthly better if you:
if (!sspc->tx) bail();
while (sspc->tx != sspc->tx_end) { if (sspc->timing_wr) { int timeout = 100;
.... } }
it'll decrease one indentation level.
> +static void start_bitbanging(struct ssp_drv_context *sspc)
I would prefix with ssp_
> +static int handle_message(struct ssp_drv_context *sspc) > +{ > + struct chip_data *chip = NULL; > + struct spi_transfer *transfer = NULL; > + void *reg = sspc->ioaddr; > + u32 cr1; > + struct device *dev = &sspc->pdev->dev; > + struct spi_message *msg = sspc->cur_msg; > + > + chip = spi_get_ctldata(msg->spi); > + > + /* We handle only one transfer message since the protocol module has to > + control the out of band signaling. */
wrong comment style.
> + transfer = list_entry(msg->transfers.next, struct spi_transfer, > + transfer_list); > + > + /* Check transfer length */ > + if (unlikely((transfer->len > MAX_SPI_TRANSFER_SIZE) || > + (transfer->len == 0))) { > + dev_warn(dev, "transfer length null or greater than %d\n", > + MAX_SPI_TRANSFER_SIZE); > + dev_warn(dev, "length = %d\n", transfer->len); > + msg->status = -EINVAL; > + > + if (msg->complete) > + msg->complete(msg->context); > + complete(&sspc->msg_done); > + return 0; > + } > + > + /* Flush any remaining data (in case of failed previous transfer) */ > + flush(sspc); > + > + sspc->tx = (void *)transfer->tx_buf; > + sspc->rx = (void *)transfer->rx_buf; > + sspc->len = transfer->len; > + sspc->write = chip->write; > + sspc->read = chip->read; > + > + if (likely(chip->dma_enabled)) { > + sspc->dma_mapped = map_dma_buffers(sspc); > + if (unlikely(!sspc->dma_mapped)) > + return 0; > + } else { > + sspc->write = sspc->tx ? chip->write : null_writer; > + sspc->read = sspc->rx ? chip->read : null_reader; > + } > + sspc->tx_end = sspc->tx + transfer->len; > + sspc->rx_end = sspc->rx + transfer->len; > + write_SSSR(sspc->clear_sr, reg); > + > + /* setup the CR1 control register */ > + cr1 = chip->cr1 | sspc->cr1_sig; > + > + if (likely(sspc->quirks & QUIRKS_DMA_USE_NO_TRAIL)) { > + /* in case of len smaller than burst size, adjust the RX */ > + /* threshold. All other cases will use the default threshold */ > + /* value. The RX fifo threshold must be aligned with the DMA */ > + /* RX transfer size, which may be limited to a multiple of 4 */ > + /* bytes due to 32bits DDR access. */
wrong comment style
> +static int ssp_spi_probe(struct pci_dev *pdev, > + const struct pci_device_id *ent) > +{ > + struct device *dev = &pdev->dev; > + struct spi_master *master; > + struct ssp_drv_context *sspc = 0; > + int status; > + u32 iolen = 0; > + u8 ssp_cfg; > + int pos; > + void __iomem *syscfg_ioaddr; > + unsigned long syscfg; > + > + /* Check if the SSP we are probed for has been allocated */ > + /* to operate as SPI. This information is retreived from */ > + /* the field adid of the Vendor-Specific PCI capability */ > + /* which is used as a configuration register. */
wrong comment style
> +static int ssp_spi_runtime_suspend(struct device *dev) > +{ > + return 0; > +} > + > +static int ssp_spi_runtime_resume(struct device *dev) > +{ > + return 0; > +}
why even add these if they're no-ops ?
> +static int __init ssp_spi_init(void) > +{ > + return pci_register_driver(&ssp_spi_driver); > +} > + > +late_initcall(ssp_spi_init);
does it have to be late ? Can't you just use module_pci_driver() instead ?
> @@ -0,0 +1,330 @@ > +/* > + * Copyright (C) Intel 2013 > + * > + * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + * > + * This program is free software; you can redistribute it and/or modify > + * it under the terms of the GNU General Public License as published by > + * the Free Software Foundation; either version 2 of the License, or > + * (at your option) any later version. companies usually don't like this "at your option any later version" statement. Usually it's GPL2 only...
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