diff options
Diffstat (limited to 'target/linux/brcm2708/patches-4.9/950-0112-i2c-bcm2835-Add-support-for-dynamic-clock.patch')
| -rw-r--r-- | target/linux/brcm2708/patches-4.9/950-0112-i2c-bcm2835-Add-support-for-dynamic-clock.patch | 117 |
1 files changed, 117 insertions, 0 deletions
diff --git a/target/linux/brcm2708/patches-4.9/950-0112-i2c-bcm2835-Add-support-for-dynamic-clock.patch b/target/linux/brcm2708/patches-4.9/950-0112-i2c-bcm2835-Add-support-for-dynamic-clock.patch new file mode 100644 index 0000000..afe2b22 --- /dev/null +++ b/target/linux/brcm2708/patches-4.9/950-0112-i2c-bcm2835-Add-support-for-dynamic-clock.patch @@ -0,0 +1,117 @@ +From ce8663f1f101f8c7b9037c31269b0b31373737ad Mon Sep 17 00:00:00 2001 +From: =?UTF-8?q?Noralf=20Tr=C3=B8nnes?= <noralf@tronnes.org> +Date: Tue, 27 Sep 2016 01:00:08 +0200 +Subject: [PATCH] i2c: bcm2835: Add support for dynamic clock +MIME-Version: 1.0 +Content-Type: text/plain; charset=UTF-8 +Content-Transfer-Encoding: 8bit + +Support a dynamic clock by reading the frequency and setting the +divisor in the transfer function instead of during probe. + +Signed-off-by: Noralf Trønnes <noralf@tronnes.org> +Reviewed-by: Martin Sperl <kernel@martin.sperl.org> +--- + drivers/i2c/busses/i2c-bcm2835.c | 51 +++++++++++++++++++++++++--------------- + 1 file changed, 32 insertions(+), 19 deletions(-) + +--- a/drivers/i2c/busses/i2c-bcm2835.c ++++ b/drivers/i2c/busses/i2c-bcm2835.c +@@ -58,6 +58,7 @@ struct bcm2835_i2c_dev { + void __iomem *regs; + struct clk *clk; + int irq; ++ u32 bus_clk_rate; + struct i2c_adapter adapter; + struct completion completion; + struct i2c_msg *curr_msg; +@@ -78,6 +79,30 @@ static inline u32 bcm2835_i2c_readl(stru + return readl(i2c_dev->regs + reg); + } + ++static int bcm2835_i2c_set_divider(struct bcm2835_i2c_dev *i2c_dev) ++{ ++ u32 divider; ++ ++ divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), ++ i2c_dev->bus_clk_rate); ++ /* ++ * Per the datasheet, the register is always interpreted as an even ++ * number, by rounding down. In other words, the LSB is ignored. So, ++ * if the LSB is set, increment the divider to avoid any issue. ++ */ ++ if (divider & 1) ++ divider++; ++ if ((divider < BCM2835_I2C_CDIV_MIN) || ++ (divider > BCM2835_I2C_CDIV_MAX)) { ++ dev_err_ratelimited(i2c_dev->dev, "Invalid clock-frequency\n"); ++ return -EINVAL; ++ } ++ ++ bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); ++ ++ return 0; ++} ++ + static void bcm2835_fill_txfifo(struct bcm2835_i2c_dev *i2c_dev) + { + u32 val; +@@ -224,7 +249,7 @@ static int bcm2835_i2c_xfer(struct i2c_a + { + struct bcm2835_i2c_dev *i2c_dev = i2c_get_adapdata(adap); + unsigned long time_left; +- int i; ++ int i, ret; + + for (i = 0; i < (num - 1); i++) + if (msgs[i].flags & I2C_M_RD) { +@@ -233,6 +258,10 @@ static int bcm2835_i2c_xfer(struct i2c_a + return -EOPNOTSUPP; + } + ++ ret = bcm2835_i2c_set_divider(i2c_dev); ++ if (ret) ++ return ret; ++ + i2c_dev->curr_msg = msgs; + i2c_dev->num_msgs = num; + reinit_completion(&i2c_dev->completion); +@@ -282,7 +311,6 @@ static int bcm2835_i2c_probe(struct plat + { + struct bcm2835_i2c_dev *i2c_dev; + struct resource *mem, *irq; +- u32 bus_clk_rate, divider; + int ret; + struct i2c_adapter *adap; + +@@ -306,28 +334,13 @@ static int bcm2835_i2c_probe(struct plat + } + + ret = of_property_read_u32(pdev->dev.of_node, "clock-frequency", +- &bus_clk_rate); ++ &i2c_dev->bus_clk_rate); + if (ret < 0) { + dev_warn(&pdev->dev, + "Could not read clock-frequency property\n"); +- bus_clk_rate = 100000; ++ i2c_dev->bus_clk_rate = 100000; + } + +- divider = DIV_ROUND_UP(clk_get_rate(i2c_dev->clk), bus_clk_rate); +- /* +- * Per the datasheet, the register is always interpreted as an even +- * number, by rounding down. In other words, the LSB is ignored. So, +- * if the LSB is set, increment the divider to avoid any issue. +- */ +- if (divider & 1) +- divider++; +- if ((divider < BCM2835_I2C_CDIV_MIN) || +- (divider > BCM2835_I2C_CDIV_MAX)) { +- dev_err(&pdev->dev, "Invalid clock-frequency\n"); +- return -ENODEV; +- } +- bcm2835_i2c_writel(i2c_dev, BCM2835_I2C_DIV, divider); +- + irq = platform_get_resource(pdev, IORESOURCE_IRQ, 0); + if (!irq) { + dev_err(&pdev->dev, "No IRQ resource\n"); |