From: Neil Armstrong narmstrong@baylibre.com
commit 09992025dacd258c823f50e82db09d7ef06cdac4 upstream.
At the end of a message, the HW gets a reset in meson_spicc_unprepare_transfer(), this resets the SPICC_CONREG register and notably the value set by the Common Clock Framework.
This is problematic because: - the register value CCF can be different from the corresponding CCF cached rate - CCF is allowed to change the clock rate whenever the HW state
This introduces: - local pow2 clock ops checking the HW state before allowing a clock operation - separation of legacy pow2 clock patch and new enhanced clock path - SPICC_CONREG datarate value is now value kepts across messages
It has been checked that: - SPICC_CONREG datarate value is kept across messages - CCF is only allowed to change the SPICC_CONREG datarate value when busy - SPICC_CONREG datarate value is correct for each transfer
This didn't appear before commit 3e0cf4d3fc29 ("spi: meson-spicc: add a linear clock divider support") because we recalculated and wrote the rate for each xfer.
Fixes: 3e0cf4d3fc29 ("spi: meson-spicc: add a linear clock divider support") Reported-by: Da Xue da@libre.computer Signed-off-by: Neil Armstrong narmstrong@baylibre.com Link: https://lore.kernel.org/r/20220811134445.678446-1-narmstrong@baylibre.com Signed-off-by: Mark Brown broonie@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- drivers/spi/spi-meson-spicc.c | 129 ++++++++++++++++++++++++++++++++---------- 1 file changed, 101 insertions(+), 28 deletions(-)
--- a/drivers/spi/spi-meson-spicc.c +++ b/drivers/spi/spi-meson-spicc.c @@ -156,6 +156,7 @@ struct meson_spicc_device { void __iomem *base; struct clk *core; struct clk *pclk; + struct clk_divider pow2_div; struct clk *clk; struct spi_message *message; struct spi_transfer *xfer; @@ -168,6 +169,8 @@ struct meson_spicc_device { unsigned long xfer_remain; };
+#define pow2_clk_to_spicc(_div) container_of(_div, struct meson_spicc_device, pow2_div) + static void meson_spicc_oen_enable(struct meson_spicc_device *spicc) { u32 conf; @@ -421,7 +424,7 @@ static int meson_spicc_prepare_message(s { struct meson_spicc_device *spicc = spi_master_get_devdata(master); struct spi_device *spi = message->spi; - u32 conf = 0; + u32 conf = readl_relaxed(spicc->base + SPICC_CONREG) & SPICC_DATARATE_MASK;
/* Store current message */ spicc->message = message; @@ -458,8 +461,6 @@ static int meson_spicc_prepare_message(s /* Select CS */ conf |= FIELD_PREP(SPICC_CS_MASK, spi->chip_select);
- /* Default Clock rate core/4 */ - /* Default 8bit word */ conf |= FIELD_PREP(SPICC_BITLENGTH_MASK, 8 - 1);
@@ -476,12 +477,16 @@ static int meson_spicc_prepare_message(s static int meson_spicc_unprepare_transfer(struct spi_master *master) { struct meson_spicc_device *spicc = spi_master_get_devdata(master); + u32 conf = readl_relaxed(spicc->base + SPICC_CONREG) & SPICC_DATARATE_MASK;
/* Disable all IRQs */ writel(0, spicc->base + SPICC_INTREG);
device_reset_optional(&spicc->pdev->dev);
+ /* Set default configuration, keeping datarate field */ + writel_relaxed(conf, spicc->base + SPICC_CONREG); + return 0; }
@@ -518,14 +523,60 @@ static void meson_spicc_cleanup(struct s * Clk path for G12A series: * pclk -> pow2 fixed div -> pow2 div -> mux -> out * pclk -> enh fixed div -> enh div -> mux -> out + * + * The pow2 divider is tied to the controller HW state, and the + * divider is only valid when the controller is initialized. + * + * A set of clock ops is added to make sure we don't read/set this + * clock rate while the controller is in an unknown state. */
-static int meson_spicc_clk_init(struct meson_spicc_device *spicc) +static unsigned long meson_spicc_pow2_recalc_rate(struct clk_hw *hw, + unsigned long parent_rate) +{ + struct clk_divider *divider = to_clk_divider(hw); + struct meson_spicc_device *spicc = pow2_clk_to_spicc(divider); + + if (!spicc->master->cur_msg || !spicc->master->busy) + return 0; + + return clk_divider_ops.recalc_rate(hw, parent_rate); +} + +static int meson_spicc_pow2_determine_rate(struct clk_hw *hw, + struct clk_rate_request *req) +{ + struct clk_divider *divider = to_clk_divider(hw); + struct meson_spicc_device *spicc = pow2_clk_to_spicc(divider); + + if (!spicc->master->cur_msg || !spicc->master->busy) + return -EINVAL; + + return clk_divider_ops.determine_rate(hw, req); +} + +static int meson_spicc_pow2_set_rate(struct clk_hw *hw, unsigned long rate, + unsigned long parent_rate) +{ + struct clk_divider *divider = to_clk_divider(hw); + struct meson_spicc_device *spicc = pow2_clk_to_spicc(divider); + + if (!spicc->master->cur_msg || !spicc->master->busy) + return -EINVAL; + + return clk_divider_ops.set_rate(hw, rate, parent_rate); +} + +const struct clk_ops meson_spicc_pow2_clk_ops = { + .recalc_rate = meson_spicc_pow2_recalc_rate, + .determine_rate = meson_spicc_pow2_determine_rate, + .set_rate = meson_spicc_pow2_set_rate, +}; + +static int meson_spicc_pow2_clk_init(struct meson_spicc_device *spicc) { struct device *dev = &spicc->pdev->dev; - struct clk_fixed_factor *pow2_fixed_div, *enh_fixed_div; - struct clk_divider *pow2_div, *enh_div; - struct clk_mux *mux; + struct clk_fixed_factor *pow2_fixed_div; struct clk_init_data init; struct clk *clk; struct clk_parent_data parent_data[2]; @@ -560,31 +611,45 @@ static int meson_spicc_clk_init(struct m if (WARN_ON(IS_ERR(clk))) return PTR_ERR(clk);
- pow2_div = devm_kzalloc(dev, sizeof(*pow2_div), GFP_KERNEL); - if (!pow2_div) - return -ENOMEM; - snprintf(name, sizeof(name), "%s#pow2_div", dev_name(dev)); init.name = name; - init.ops = &clk_divider_ops; - init.flags = CLK_SET_RATE_PARENT; + init.ops = &meson_spicc_pow2_clk_ops; + /* + * Set NOCACHE here to make sure we read the actual HW value + * since we reset the HW after each transfer. + */ + init.flags = CLK_SET_RATE_PARENT | CLK_GET_RATE_NOCACHE; parent_data[0].hw = &pow2_fixed_div->hw; init.num_parents = 1;
- pow2_div->shift = 16, - pow2_div->width = 3, - pow2_div->flags = CLK_DIVIDER_POWER_OF_TWO, - pow2_div->reg = spicc->base + SPICC_CONREG; - pow2_div->hw.init = &init; + spicc->pow2_div.shift = 16, + spicc->pow2_div.width = 3, + spicc->pow2_div.flags = CLK_DIVIDER_POWER_OF_TWO, + spicc->pow2_div.reg = spicc->base + SPICC_CONREG; + spicc->pow2_div.hw.init = &init;
- clk = devm_clk_register(dev, &pow2_div->hw); - if (WARN_ON(IS_ERR(clk))) - return PTR_ERR(clk); + spicc->clk = devm_clk_register(dev, &spicc->pow2_div.hw); + if (WARN_ON(IS_ERR(spicc->clk))) + return PTR_ERR(spicc->clk);
- if (!spicc->data->has_enhance_clk_div) { - spicc->clk = clk; - return 0; - } + return 0; +} + +static int meson_spicc_enh_clk_init(struct meson_spicc_device *spicc) +{ + struct device *dev = &spicc->pdev->dev; + struct clk_fixed_factor *enh_fixed_div; + struct clk_divider *enh_div; + struct clk_mux *mux; + struct clk_init_data init; + struct clk *clk; + struct clk_parent_data parent_data[2]; + char name[64]; + + memset(&init, 0, sizeof(init)); + memset(&parent_data, 0, sizeof(parent_data)); + + init.parent_data = parent_data;
/* algorithm for enh div: rate = freq / 2 / (N + 1) */
@@ -637,7 +702,7 @@ static int meson_spicc_clk_init(struct m snprintf(name, sizeof(name), "%s#sel", dev_name(dev)); init.name = name; init.ops = &clk_mux_ops; - parent_data[0].hw = &pow2_div->hw; + parent_data[0].hw = &spicc->pow2_div.hw; parent_data[1].hw = &enh_div->hw; init.num_parents = 2; init.flags = CLK_SET_RATE_PARENT; @@ -754,12 +819,20 @@ static int meson_spicc_probe(struct plat
meson_spicc_oen_enable(spicc);
- ret = meson_spicc_clk_init(spicc); + ret = meson_spicc_pow2_clk_init(spicc); if (ret) { - dev_err(&pdev->dev, "clock registration failed\n"); + dev_err(&pdev->dev, "pow2 clock registration failed\n"); goto out_clk; }
+ if (spicc->data->has_enhance_clk_div) { + ret = meson_spicc_enh_clk_init(spicc); + if (ret) { + dev_err(&pdev->dev, "clock registration failed\n"); + goto out_clk; + } + } + ret = devm_spi_register_master(&pdev->dev, master); if (ret) { dev_err(&pdev->dev, "spi master registration failed\n");