From patchwork Tue Oct 9 10:44:47 2012 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Subject: [05/11] fsmc: Implement ready/busy through gpio pin Date: Tue, 09 Oct 2012 00:44:47 -0000 From: Vipin Kumar X-Patchwork-Id: 190271 Message-Id: To: , Cc: Vipin Kumar , linus.walleij@linaro.org, spear-devel@list.st.com, plagnioj@jcrosoft.com, linux-arm-kernel@lists.infradead.org The NAND devices have a ready/busy (active low) output which is connected to the FSMC controller FSMC_RnB pin The CPU can work in following two ways * CPU keeps waiting for a ready response and it halts until it receives a ready response from NAND device. This halts the ldr instruction in between and in effect holds the CPU down for a number of cycles. During this period, CPU can't even service interrupts. This behavior is enabled via WAIT_ON bit of FSMC controller * CPU merely issues the command and does not wait for response. The NAND device is later probed for being ready by reading the NAND_RnB signal Until now, WAIT_ON was enabled by default. This patch implements reading the device ready state through a gpio. The gpio number is passed via DT and this patch also adds a corresponding binding for fsmc Signed-off-by: Vipin Kumar --- .../devicetree/bindings/mtd/fsmc-nand.txt | 5 ++ drivers/mtd/nand/fsmc_nand.c | 54 +++++++++++++++++++--- include/linux/mtd/fsmc.h | 11 +++++ 3 files changed, 64 insertions(+), 6 deletions(-) diff --git a/Documentation/devicetree/bindings/mtd/fsmc-nand.txt b/Documentation/devicetree/bindings/mtd/fsmc-nand.txt index 6a7fc43..598bca2 100644 --- a/Documentation/devicetree/bindings/mtd/fsmc-nand.txt +++ b/Documentation/devicetree/bindings/mtd/fsmc-nand.txt @@ -25,6 +25,11 @@ Optional properties: period of hclk ie a number 4 in thold with hclk = 166MHz means that thold = (1000 / 166) * 4 ns = 24.09ns +- st,ready-busy: Should contain either of "rb-gpio" or "rb-wait". When + this property is not defined, the default is to use rb-wait. +- st,rb-gpios: When the st,ready-busy is defined as "rb-gpio", a gpio + pin number is defined in this property + Example: fsmc: flash@d1800000 { diff --git a/drivers/mtd/nand/fsmc_nand.c b/drivers/mtd/nand/fsmc_nand.c index f3d69b3..eaffd3b 100644 --- a/drivers/mtd/nand/fsmc_nand.c +++ b/drivers/mtd/nand/fsmc_nand.c @@ -22,6 +22,7 @@ #include #include #include +#include #include #include #include @@ -32,6 +33,7 @@ #include #include #include +#include #include #include #include @@ -289,6 +291,7 @@ static struct fsmc_eccplace fsmc_ecc4_sp_place = { * @write_dma_chan: DMA channel for write access to NAND * @dma_access_complete: Completion structure * + * @rb_pin: Ready/Busy data * @dev_timings: Timings to be programmed in controller * @partitions: Partition info for a NAND Flash * @nr_partitions: Total number of partition of a NAND flash @@ -322,6 +325,7 @@ struct fsmc_nand_data { struct completion dma_access_complete; /* Recieved from plat data */ + struct fsmc_rbpin *rbpin; struct fsmc_nand_timings *dev_timings; struct mtd_partition *partitions; unsigned int nr_partitions; @@ -410,12 +414,16 @@ static void fsmc_cmd_ctrl(struct mtd_info *mtd, int cmd, unsigned int ctrl) * This routine initializes timing parameters related to NAND memory access in * FSMC registers */ -static void fsmc_nand_setup(void __iomem *regs, uint32_t bank, - uint32_t busw, struct fsmc_nand_timings *timings) +static void fsmc_nand_setup(void __iomem *regs, uint32_t bank, uint32_t busw, + struct fsmc_nand_timings *timings, + struct fsmc_rbpin *rbpin) { - uint32_t value = FSMC_DEVTYPE_NAND | FSMC_ENABLE | FSMC_WAITON; + uint32_t value = FSMC_DEVTYPE_NAND | FSMC_ENABLE; uint32_t tclr, tar, thiz, thold, twait, tset; + if (!rbpin || (rbpin->use_pin == FSMC_RB_WAIT)) + value |= FSMC_WAITON; + tclr = (timings->tclr & FSMC_TCLR_MASK) << FSMC_TCLR_SHIFT; tar = (timings->tar & FSMC_TAR_MASK) << FSMC_TAR_SHIFT; thiz = (timings->thiz & FSMC_THIZ_MASK) << FSMC_THIZ_SHIFT; @@ -857,6 +865,14 @@ static bool filter(struct dma_chan *chan, void *slave) return true; } +static int fsmc_dev_ready(struct mtd_info *mtd) +{ + struct fsmc_nand_data *host = container_of(mtd, + struct fsmc_nand_data, mtd); + + return !!gpio_get_value(host->rbpin->gpio_pin); +} + #ifdef CONFIG_OF static int __devinit fsmc_nand_probe_config_dt(struct platform_device *pdev, struct device_node *np) @@ -870,7 +886,9 @@ static int __devinit fsmc_nand_probe_config_dt(struct platform_device *pdev, .twait = FSMC_TWAIT_6, .tset = FSMC_TSET_0, }; + const char *rb; u32 val; + enum of_gpio_flags flags; /* Set default NAND width to 8 bits */ pdata->width = 8; @@ -911,6 +929,14 @@ static int __devinit fsmc_nand_probe_config_dt(struct platform_device *pdev, sizeof(default_timings)); } + if (!of_property_read_string(np, "st,ready-busy", &rb) && + !strcmp(rb, "rb-gpio")) { + pdata->rbpin.use_pin = FSMC_RB_GPIO; + pdata->rbpin.gpio_pin = + of_get_named_gpio_flags(np, "st,rb-gpios", 0, &flags); + } else + pdata->rbpin.use_pin = FSMC_RB_WAIT; + return 0; } #else @@ -1049,6 +1075,8 @@ static int __init fsmc_nand_probe(struct platform_device *pdev) host->nr_partitions = pdata->nr_partitions; host->dev = &pdev->dev; host->dev_timings = &pdata->nand_timings; + host->rbpin = &pdata->rbpin; + host->mode = pdata->mode; host->max_banks = pdata->max_banks; @@ -1074,6 +1102,18 @@ static int __init fsmc_nand_probe(struct platform_device *pdev) nand->select_chip = fsmc_select_chip; nand->badblockbits = 7; + if (host->rbpin->use_pin != FSMC_RB_WAIT) + nand->dev_ready = fsmc_dev_ready; + + if (host->rbpin->use_pin == FSMC_RB_GPIO) { + ret = gpio_request(host->rbpin->gpio_pin, "fsmc-rb"); + if (ret < 0) { + dev_err(&pdev->dev, "gpio request fail: %d\n", + host->rbpin->gpio_pin); + goto err_gpio_req; + } + } + if (pdata->width == FSMC_NAND_BW16) nand->options |= NAND_BUSWIDTH_16; @@ -1107,7 +1147,7 @@ static int __init fsmc_nand_probe(struct platform_device *pdev) for (bank = 0; bank < host->max_banks; bank++) fsmc_nand_setup(host->regs_va, bank, nand->options & NAND_BUSWIDTH_16, - host->dev_timings); + host->dev_timings, host->rbpin); if (AMBA_REV_BITS(host->pid) >= 8) { nand->ecc.read_page = fsmc_read_page_hwecc; @@ -1211,6 +1251,9 @@ err_req_write_chnl: if (host->mode == USE_DMA_ACCESS) dma_release_channel(host->read_dma_chan); err_req_read_chnl: + if (host->rbpin->use_pin == FSMC_RB_GPIO) + gpio_free(host->rbpin->gpio_pin); +err_gpio_req: clk_disable_unprepare(host->clk); err_clk_prepare_enable: clk_put(host->clk); @@ -1260,8 +1303,7 @@ static int fsmc_nand_resume(struct device *dev) for (bank = 0; bank < host->max_banks; bank++) fsmc_nand_setup(host->regs_va, bank, host->nand.options & NAND_BUSWIDTH_16, - host->dev_timings); - + host->dev_timings, host->rbpin); } return 0; } diff --git a/include/linux/mtd/fsmc.h b/include/linux/mtd/fsmc.h index 4fbdce4..eed22a1 100644 --- a/include/linux/mtd/fsmc.h +++ b/include/linux/mtd/fsmc.h @@ -130,6 +130,16 @@ struct fsmc_nand_timings { uint8_t tset; }; +enum rbpin { + FSMC_RB_WAIT = 0, + FSMC_RB_GPIO, +}; + +struct fsmc_rbpin { + enum rbpin use_pin; + uint32_t gpio_pin; +}; + enum access_mode { USE_DMA_ACCESS = 1, USE_WORD_ACCESS, @@ -149,6 +159,7 @@ enum access_mode { */ struct fsmc_nand_platform_data { struct fsmc_nand_timings nand_timings; + struct fsmc_rbpin rbpin; struct mtd_partition *partitions; unsigned int nr_partitions; unsigned int options;