Messages in this thread | | | Date | Thu, 28 Jun 2018 09:00:34 +0200 | From | Miquel Raynal <> | Subject | Re: [PATCH 2/2] mtd: rawnand: meson: add support for Amlogic NAND flash controller |
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Hi Kevin,
On Wed, 27 Jun 2018 16:33:43 -0700, Kevin Hilman <khilman@baylibre.com> wrote:
> Hi Boris, > > Boris Brezillon <boris.brezillon@bootlin.com> writes: > > > Hi Yixun, > > > > On Wed, 13 Jun 2018 16:13:14 +0000 > > Yixun Lan <yixun.lan@amlogic.com> wrote: > > > >> From: Liang Yang <liang.yang@amlogic.com> > >> > >> Add initial support for the Amlogic NAND flash controller which found > >> in the Meson-GXBB/GXL/AXG SoCs. > >> > >> Singed-off-by: Liang Yang <liang.yang@amlogic.com> > >> Signed-off-by: Yixun Lan <yixun.lan@amlogic.com> > >> --- > >> drivers/mtd/nand/raw/Kconfig | 8 + > >> drivers/mtd/nand/raw/Makefile | 3 + > >> drivers/mtd/nand/raw/meson_nand.c | 1422 +++++++++++++++++++++++++++++ > >> 3 files changed, 1433 insertions(+) > >> create mode 100644 drivers/mtd/nand/raw/meson_nand.c > > > > Can you run checkpatch.pl --strict and fix the coding style issues? > > > >> > >> diff --git a/drivers/mtd/nand/raw/Kconfig b/drivers/mtd/nand/raw/Kconfig > >> index 19a2b283fbbe..b3c17a3ca8f4 100644 > >> --- a/drivers/mtd/nand/raw/Kconfig > >> +++ b/drivers/mtd/nand/raw/Kconfig > >> @@ -534,4 +534,12 @@ config MTD_NAND_MTK > >> Enables support for NAND controller on MTK SoCs. > >> This controller is found on mt27xx, mt81xx, mt65xx SoCs. > >> > >> +config MTD_NAND_MESON > >> + tristate "Support for NAND flash controller on Amlogic's Meson SoCs" > >> + depends on ARCH_MESON || COMPILE_TEST > >> + select COMMON_CLK_REGMAP_MESON > >> + select MFD_SYSCON > >> + help > >> + Enables support for NAND controller on Amlogic's Meson SoCs. > >> + > >> endif # MTD_NAND > >> diff --git a/drivers/mtd/nand/raw/Makefile b/drivers/mtd/nand/raw/Makefile > >> index 165b7ef9e9a1..cdf6162f38c3 100644 > >> --- a/drivers/mtd/nand/raw/Makefile > >> +++ b/drivers/mtd/nand/raw/Makefile > >> @@ -1,5 +1,7 @@ > >> # SPDX-License-Identifier: GPL-2.0 > >> > >> +ccflags-$(CONFIG_MTD_NAND_MESON) += -I$(srctree)/drivers/clk/meson > > > > Please don't do that. If you need to expose common regs, put them > > in include/linux/soc/meson/. I'm also not sure why you need to access > > the clk regs directly. Why can't you expose the MMC/NAND clk as a clk > > provider whose driver would be placed in drivers/clk and which would use > > the mmc syscon. This way the same clk driver could be used for both > > MMC and NAND clk indifferently, and the NAND driver would be much > > simpler. > > [...] > > >> + > >> + return 0; > >> +} > >> + > >> +static const char * sd_emmc_ext_clk0_parent_names[MUX_CLK_NUM_PARENTS]; > >> + > >> +static struct clk_regmap sd_emmc_c_ext_clk0_sel = { > >> + .data = &(struct clk_regmap_mux_data){ > >> + .offset = SD_EMMC_CLOCK, > >> + .mask = 0x3, > >> + .shift = 6, > >> + }, > >> + .hw.init = &(struct clk_init_data) { > >> + .name = "sd_emmc_c_nand_clk_mux", > >> + .ops = &clk_regmap_mux_ops, > >> + .parent_names = sd_emmc_ext_clk0_parent_names, > >> + .num_parents = ARRAY_SIZE(sd_emmc_ext_clk0_parent_names), > >> + .flags = CLK_SET_RATE_PARENT, > >> + }, > >> +}; > >> + > >> +static struct clk_regmap sd_emmc_c_ext_clk0_div = { > >> + .data = &(struct clk_regmap_div_data){ > >> + .offset = SD_EMMC_CLOCK, > >> + .shift = 0, > >> + .width = 6, > >> + .flags = CLK_DIVIDER_ROUND_CLOSEST | CLK_DIVIDER_ONE_BASED, > >> + }, > >> + .hw.init = &(struct clk_init_data) { > >> + .name = "sd_emmc_c_nand_clk_div", > >> + .ops = &clk_regmap_divider_ops, > >> + .parent_names = (const char *[]){ "sd_emmc_c_nand_clk_mux" }, > >> + .num_parents = 1, > >> + .flags = CLK_SET_RATE_PARENT, > >> + }, > >> +}; > >> + > >> +static int meson_nfc_clk_init(struct meson_nfc *nfc) > >> +{ > >> + struct clk_regmap *mux = &sd_emmc_c_ext_clk0_sel; > >> + struct clk_regmap *div = &sd_emmc_c_ext_clk0_div; > >> + struct clk *clk; > >> + int i, ret; > >> + > >> + /* request core clock */ > >> + nfc->core_clk = devm_clk_get(nfc->dev, "core"); > >> + if (IS_ERR(nfc->core_clk)) { > >> + dev_err(nfc->dev, "failed to get core clk\n"); > >> + return PTR_ERR(nfc->core_clk); > >> + } > >> + > >> + /* init SD_EMMC_CLOCK to sane defaults w/min clock rate */ > >> + regmap_update_bits(nfc->reg_clk, 0, > >> + CLK_SELECT_NAND | CLK_ALWAYS_ON | CLK_DIV_MASK, > >> + CLK_SELECT_NAND | CLK_ALWAYS_ON | CLK_DIV_MASK); > >> + > >> + /* get the mux parents */ > >> + for (i = 0; i < MUX_CLK_NUM_PARENTS; i++) { > >> + char name[16]; > >> + > >> + snprintf(name, sizeof(name), "clkin%d", i); > >> + clk = devm_clk_get(nfc->dev, name); > >> + if (IS_ERR(clk)) { > >> + if (clk != ERR_PTR(-EPROBE_DEFER)) > >> + dev_err(nfc->dev, "Missing clock %s\n", name); > >> + return PTR_ERR(clk); > >> + } > >> + > >> + sd_emmc_ext_clk0_parent_names[i] = __clk_get_name(clk); > >> + } > >> + > >> + mux->map = nfc->reg_clk; > >> + clk = devm_clk_register(nfc->dev, &mux->hw); > >> + if (WARN_ON(IS_ERR(clk))) > >> + return PTR_ERR(clk); > >> + > >> + div->map = nfc->reg_clk; > >> + nfc->device_clk = devm_clk_register(nfc->dev, &div->hw); > >> + if (WARN_ON(IS_ERR(nfc->device_clk))) > >> + return PTR_ERR(nfc->device_clk); > >> + > >> + ret = clk_prepare_enable(nfc->core_clk); > >> + if (ret) { > >> + dev_err(nfc->dev, "failed to enable core clk\n"); > >> + return ret; > >> + } > >> + > >> + ret = clk_prepare_enable(nfc->device_clk); > >> + if (ret) { > >> + dev_err(nfc->dev, "failed to enable device clk\n"); > >> + clk_disable_unprepare(nfc->core_clk); > >> + return ret; > >> + } > >> + > >> + return 0; > >> +} > > > > > > As said above, I don't like having a clk driver here, especially since > > the registers you're accessing are not part of the NAND controller > > registers. Please try to create a driver in drivers/clk/ for that. > > We went back and forth on this one on some off-list reviews. > > Had we known that the NAND controller was (re)using the clock registers > internal to the MMC IP block from the beginning, we would have written a > clock provider in drivers/clk for this, and shared it. > > However, when I wrote the MMC driver[1] (already upstream) along with > the bindings[2], we did not fathom that the internal mux and divider > would be "borrowed" by another device. :( > > We only recently found out that the NAND controller "borrows" one of the > MMC clocks, whose registers are inside the MMC range. Taking the clock > out of the MMC driver and into its own clock-provider implies redoing > the MMC driver, as well as its bindings, which we wanted to avoid > (especially the binding changes.) > > We (I can take the blame) decided that since the MMC and NAND are > mutually exclusive (they also share pins), that allowing NAND to reuse > the MMC range would be a good compromise. The DT still accurately > describes the hardware, but we don't have to throw a large wrench into > the DT bindings just for a newly discovered shared clock. > > I agree, it's not the prettiest thing, but when we cannot know the full > details of the hardware when we start, sometimes we end up in a bit of a > mess that requires some compromise.
I totally understand your situation but as MMC and NAND are mutually exclusive, how is this a problem to have a dedicated clock driver used only by the NAND controller (as maybe a first step)? I mean, if you don't change the MMC bindings, then the MMC driver will still use its own 'local' clock driver, right? I don't know if you can have two nodes reserving the same address range though.
> > Kevin > > [1] drivers/mmc/host/meson-gx-mmc.c > [2] Documentation/devicetree/bindings/mmc/amlogic,meson-gx.txt
Thanks, Miquèl
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