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Fri, 22 Apr 2022 15:57:16 +0000 From: icenowy@outlook.com To: Mark Brown , Chen-Yu Tsai , Jernej Skrabec , Samuel Holland , Maxime Ripard Cc: linux-spi@vger.kernel.org, devicetree@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-sunxi@lists.linux.dev, linux-kernel@vger.kernel.org, Icenowy Zheng Subject: [PATCH 3/4] spi: sun6i: add quirk for in-controller clock divider Date: Fri, 22 Apr 2022 23:56:38 +0800 Message-ID: X-Mailer: git-send-email 2.35.1 In-Reply-To: <20220422155639.1071645-1-icenowy@outlook.com> References: <20220422155639.1071645-1-icenowy@outlook.com> X-TMN: [6on+UoLO1ATpsFxi0pyPJsItMb+i9p/A] X-ClientProxiedBy: HK0PR01CA0059.apcprd01.prod.exchangelabs.com (2603:1096:203:a6::23) To BYAPR20MB2472.namprd20.prod.outlook.com (2603:10b6:a03:155::16) X-Microsoft-Original-Message-ID: <20220422155639.1071645-4-icenowy@outlook.com> MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 27e00b0f-5279-4cf3-da4c-08da2478c62c X-MS-TrafficTypeDiagnostic: CY4PR2001MB0917:EE_ X-Microsoft-Antispam: BCL:0; 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However now the clock divider is removed and to set the transfer clock rate it's only needed to set the SPI module clock to the target value. Add a quirk for this kind of SPI controllers. Signed-off-by: Icenowy Zheng --- drivers/spi/spi-sun6i.c | 68 +++++++++++++++++++++++------------------ 1 file changed, 38 insertions(+), 30 deletions(-) diff --git a/drivers/spi/spi-sun6i.c b/drivers/spi/spi-sun6i.c index 84c525b08ad0..fc81afc3a963 100644 --- a/drivers/spi/spi-sun6i.c +++ b/drivers/spi/spi-sun6i.c @@ -87,6 +87,7 @@ struct sun6i_spi_cfg { unsigned long fifo_depth; + bool has_clk_ctl; }; struct sun6i_spi { @@ -260,7 +261,7 @@ static int sun6i_spi_transfer_one(struct spi_master *master, struct spi_transfer *tfr) { struct sun6i_spi *sspi = spi_master_get_devdata(master); - unsigned int mclk_rate, div, div_cdr1, div_cdr2, timeout; + unsigned int div, div_cdr1, div_cdr2, timeout; unsigned int start, end, tx_time; unsigned int trig_level; unsigned int tx_len = 0, rx_len = 0; @@ -350,39 +351,44 @@ static int sun6i_spi_transfer_one(struct spi_master *master, sun6i_spi_write(sspi, SUN6I_TFR_CTL_REG, reg); - /* Ensure that we have a parent clock fast enough */ - mclk_rate = clk_get_rate(sspi->mclk); - if (mclk_rate < (2 * tfr->speed_hz)) { - clk_set_rate(sspi->mclk, 2 * tfr->speed_hz); - mclk_rate = clk_get_rate(sspi->mclk); - } + if (sspi->cfg->has_clk_ctl) { + unsigned int mclk_rate = clk_get_rate(sspi->mclk); + /* Ensure that we have a parent clock fast enough */ + if (mclk_rate < (2 * tfr->speed_hz)) { + clk_set_rate(sspi->mclk, 2 * tfr->speed_hz); + mclk_rate = clk_get_rate(sspi->mclk); + } - /* - * Setup clock divider. - * - * We have two choices there. Either we can use the clock - * divide rate 1, which is calculated thanks to this formula: - * SPI_CLK = MOD_CLK / (2 ^ cdr) - * Or we can use CDR2, which is calculated with the formula: - * SPI_CLK = MOD_CLK / (2 * (cdr + 1)) - * Wether we use the former or the latter is set through the - * DRS bit. - * - * First try CDR2, and if we can't reach the expected - * frequency, fall back to CDR1. - */ - div_cdr1 = DIV_ROUND_UP(mclk_rate, tfr->speed_hz); - div_cdr2 = DIV_ROUND_UP(div_cdr1, 2); - if (div_cdr2 <= (SUN6I_CLK_CTL_CDR2_MASK + 1)) { - reg = SUN6I_CLK_CTL_CDR2(div_cdr2 - 1) | SUN6I_CLK_CTL_DRS; - tfr->effective_speed_hz = mclk_rate / (2 * div_cdr2); + /* + * Setup clock divider. + * + * We have two choices there. Either we can use the clock + * divide rate 1, which is calculated thanks to this formula: + * SPI_CLK = MOD_CLK / (2 ^ cdr) + * Or we can use CDR2, which is calculated with the formula: + * SPI_CLK = MOD_CLK / (2 * (cdr + 1)) + * Wether we use the former or the latter is set through the + * DRS bit. + * + * First try CDR2, and if we can't reach the expected + * frequency, fall back to CDR1. + */ + div_cdr1 = DIV_ROUND_UP(mclk_rate, tfr->speed_hz); + div_cdr2 = DIV_ROUND_UP(div_cdr1, 2); + if (div_cdr2 <= (SUN6I_CLK_CTL_CDR2_MASK + 1)) { + reg = SUN6I_CLK_CTL_CDR2(div_cdr2 - 1) | SUN6I_CLK_CTL_DRS; + tfr->effective_speed_hz = mclk_rate / (2 * div_cdr2); + } else { + div = min(SUN6I_CLK_CTL_CDR1_MASK, order_base_2(div_cdr1)); + reg = SUN6I_CLK_CTL_CDR1(div); + tfr->effective_speed_hz = mclk_rate / (1 << div); + } + + sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg); } else { - div = min(SUN6I_CLK_CTL_CDR1_MASK, order_base_2(div_cdr1)); - reg = SUN6I_CLK_CTL_CDR1(div); - tfr->effective_speed_hz = mclk_rate / (1 << div); + clk_set_rate(sspi->mclk, tfr->speed_hz); } - sun6i_spi_write(sspi, SUN6I_CLK_CTL_REG, reg); /* Finally enable the bus - doing so before might raise SCK to HIGH */ reg = sun6i_spi_read(sspi, SUN6I_GBL_CTL_REG); reg |= SUN6I_GBL_CTL_BUS_ENABLE; @@ -702,10 +708,12 @@ static int sun6i_spi_remove(struct platform_device *pdev) static const struct sun6i_spi_cfg sun6i_a31_spi_cfg = { .fifo_depth = SUN6I_FIFO_DEPTH, + .has_clk_ctl = true, }; static const struct sun6i_spi_cfg sun8i_h3_spi_cfg = { .fifo_depth = SUN8I_FIFO_DEPTH, + .has_clk_ctl = true, }; static const struct of_device_id sun6i_spi_match[] = {